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Gould 400 Series
Digital Storage Oscilloscopes
Operators Manual
Gould 400 Series
Digital Storage Oscilloscopes
Operators Manual
Copyright@1990 Gould lnc., Instruments Division
(Gould Electronics Ltd.)
400 Operators Manual
Contents
Introduction
Getting Started 1
Advanced Features 2
The Menus 3
Performance Checking 4
Waveform Processing 5
Battery Unit Operation 6
Alphabetical Summary 7
Appendix 1 Error Messages A1
Appendix 2 Specification A2
Appendix 3 Remote
Operation A3
Appendix 4 Front & Back
Pictures
I Service Facilities
Contents 400 Operators Manual
Introduction 2.5 Plot
2.5.1 Internal Colour Plotter
1. Getting Started 2.5.2 Pens ti
O
1.1 Safety and Power Requirements 2.5.3 Pen Changing
1.1.1 International Safety Warning 2.5.4 Paper Selection
1.1.2 Grounding 2.5.5 Paper Loading
1.1.3 Live Parts 2.5.6 Internal plotting
1.1.4 Ventilation and Dust 2.5.7 External plots
1.1.5 Operating Temperatures 2.5.8 Plot positioning and scaling
1.1.6 Power & Frequency
Requirements 2.6 Data Transfer
1.1.7 Fuse Requirements 2.6.1 Syntax
2.6.2 Receiving Data
1.2 Using the Buttons 2.6.3 Error Status
1.3 Start-Up Display
1.4 Obtaining a Trace 2.7 Real Time Clock
1.4.1 AUTO SETUP
1.4.2 Channel Selection (Off/On/lnv) 3. The Menus
1.4.3 Coupling (AC/DC/Gnd) 3.1 Additional Buttons
3.1.1 The Numeric Buttons
1.5 Horizontal Adjustments 3.1.2 Menu Traces
1.5.1 TIME/DIVISION 3.1.3 Control
1.5.2 Aliases 3.1.4 Post Store
1.5.3 Position
1.5.4 Magnification 3.2 Control Master Menu
3.3 Status Menu
1.6 Vertical Adjustments 3.3.1 Mode
1.6.1 VOLTS/DIVISION 3.3.2 Max/Min
1.6.2 Position 3.3.3 V/Div
1.6.3 Variable/Uncalibrated 3.3.4 Probe set
1.6.4 Add 3.3.5 Timebase
3.3.6 Trigger
1.7 Manually Obtaining a Trace
1.8 Operating Hints 3.4 Display and Trigger Menu
1.8.1 Intensities too low 3.4.1 Probe ratio
1.8.2 Trace off the top or bottom 3.4.2 Max/Min
of screen 3.4.3 Dot Join
1.8.3 Trace not being acquired 3.4.4 Averaging
1.8.4 Trace unstable 3.4.5 Trig Pos'n
1.8.5 Trace has flat top or bottom
3.5 Display Intensity
2. Advanced Features 3.6 Reference Trace
2.1 Trigger Control 3.7 RS423 Interface Menu
2.1.1 Selecting Source and Coupling 3.7.1 RS423 Plot Connections
2.1.2 Level 3.7.2 RS423 Data Connections
2.1.3 Trigger Point (T)
2.1.4 Slope (+/-) 3.8 Special Functions Menu
2.1.5 Trigger Mode (Norm/Auto) 3.9 Post Store Master Menu
2.1.6 Trigger Delay 3.10 Save Trace Menu
3.11 Recall Memory Menu
2.2 Capture Facilities 3.12 Plot Menu
2.2.1 Trace Hold
2.2.2 S/Shot and Run 4. Performance checking
2.2.3 Acquisition Status-AFTS 4.1 Risetime
4.2 Bandwidth
2.3 Display Modes 4.3 Trigger sensitivity
2.4 Cursor Measurements 4.4 Trigger bandwidth
2.4.1 Cursor and Datum Selection 4.5 Timebase calibration
2.4.2 The Cursor& Datum Lines 4.6 Vertical Calibration
2.4.3 Making Measurements 4.7 Max-Min (Alias Detector)
400 Series Operators Manual Contents
5. Waveform Processing Functions Figure List
5.1 Cursor Measurements 1.2a Single Function Buttons
5.1.1 Voltage and Time 1.2b The Toggles
5.1.2 Peak-Peak 1.2c Pressure Sensitive Buttons
5.1.3 Max-Min 1.3 Start-Up Display
5.1.4 Risetime (falltime) 1.4 Obtaining a trace
5.1.5 Overshoot (preshoot) 1.4.1 An AUTO SETUP Display
5.1.6 Pulse Width 1.5 Horizontal Controls
5.1.7 Frequency, Period, Duty Cycle 1.5.2 Alias Generation
5.1.8 RMS 1.6 Vertical Controls
5.1.9 Area 2.1 Trigger Controls
2.1.6 Trace Capture with Delay
5.2 Trace Manipulation 2.2 Capture Controls
5.2.1 Filter Frequency 2.4 The Cursor and Datum Line Controls
5.2.2 Filter Current Trace 2.4.2 The Cursor and Datum Lines
5.2.3 Invert Current Trace 2.5.5 Paper Loading
5.2.4 Integrate Signal 2.5.8a Relative Plot Positions
5.2.5 Integrate Current Trace 2.5.8b Plot Dimensions
3 Menu Overview
5.3 Trace arithmetic 3.1 Numeric Buttons
3.2 Control Master Menu
5.4 Persistence/Limits Testing 3.3 A Status Menu
5.4.1 Limits 3.4 A Display and Trigger Menu
5.4.2 Persistence 3.5 Display Intensity Menu
3.6 Reference Trace Menu
6. Battery Unit Operation 3.7 An RS423 Interface Menu
3.7.1 400to Gould 6120 or HP7475 Connections
7. Alphabetical Summary of controls 3.7.2a 400 to IBM-PC/XT Connections
3.7.2b 400 to IBM-PC/AT Connections
Appendix 1: Error Messages 3.8 Special Functions Menu
3.9 Post Storage Master Menu
Appendix 2: Specification 3.10 Save Trace Menu
3.11 Recall Trace Menu
Appendix 3: Remote DC operation of the DSO 3.12 Plot Menu
5.1a Cursor Measurements Menu
Appendix 4: Front and Back Pictures 5.1b Example of Calculations on trace
5.1.1 Voltage and Time Measurement
Service Facilities 5.1.2 Peak to Peak Measurement
5.1.3 Max-Min Measurement
5.1.4 Risetime Measurement
5.1.5 Overshoot Measurement
5.1.6 Pulse Width Measurement
5.1.7 Freq. Period and Duty Cycle Measurement
5.1.9 Area Measurement
5.2 Trace Manipulation Menu
5.4 Persistence/Limits Testing Menu
6 Battery Unit Interconnections
6.2 Battery Unit Front Panel Indicators
A2 400 Series Dimensions
A3.2 DC Power Connections
A4a Rear View
A4b RS423 Connections
A4c Front Panel Controls
400 Operators Manual Introduction
Introduction
The Gould 400 series instruments are Digital Storage More advanced features of the 400 series include a com-
Oscilloscopes (DSOs). They include all the features prehensive range of menu-controlled functions. For
expected of advanced modern oscilloscopes designed for example, the Display and Trigger menu operates features
the professional engineer, whilst retaining the user- such as the trigger delay and pre-trigger display
friendliness essential for those learning to use such functions. The pre-trigger display function allows the
instruments for the first time. signal prior to the trigger point to be captured and
The 400 range consists of three basic models; the 400 the displayed.
420 and the 450. All versions can be fitted with a battery Three complete traces can be stored for future use and
unit which provides the instrument with a fully automatic recalled to the display via the Save Trace and Recall
built in Nickel Cadmium battery and charger which Trace menus respectively. With the built in battery back
allows uninterrupted operation of the DSO in the event up facility, these will be retained even when the
of an AC supply failure and complete operation instrument is switched off.
independent of an AC supply. In addition to the above features, the 420 and 450 instru-
Obtaining a trace is especially simple - just connect the ments have a built in 4 colour plotter and a battery
signal and press the Auto Setup button - the 400 does the backed Real Time Clock. This provides a simple and
rest. Having obtained a trace, readily accessible datum convenient method of obtaining permanent hard copy
lines and a cursor make it easy to take automatic timing plots of the screen display. The plots will contain the date
and voltage measurements directly from the display. On and time of acquisition together with the date and time of
the 420 and 450 models, the waveform processing plotting.
function increases the power of the cursor measurements The 450 has all the features of the 420 and has a signal
in terms of both capture and post storage analysis and bandwidth of 50MHz and an extra timebase range of
measurement functions. 50ns/div.
The innovative use of ergonomically designed pressure
sensitive push button controls provides a combination of
precision and flexibility for ease of operation.
Numbers circled in the text refer to the controls shown
on the front panel picture in Appendix 3.
Getting Started 1.1-1.1.6 400 Series Operators Manual
1.1 Safety and Power Requirements they should be removed only by suitably qualified personnel
for maintenance and repair purposes.
1.1.1 International Safety Warning
(as required for I.E.C. 348 Cat I) WARNING: Removing the covers may expose voltages in
This instrument has been designed and tested in accordance excess of 8000V at the side of the display tube; these
with IEC publication 348, and has been supplied in a safe may be present for up to one minute after the
condition. This manual contains information and warnings instrument has been disconnected from the power
which must be observed to keep the instrument in a safe source.
condition. The instrument should not be switched on if it is
damaged and it should not be used under wet conditions. 1.1.4 Ventilation and Dust
For the correct and safe use of this instrument it is essential that
The instrument relies on forced air cooling via a fan and
both operating and service personnel follow generally accepted
ventilation slots. Adequate ventilation can usually be achieved
safety procedures in addition to the safety precautions specified
by leaving a 75mm (3" gap) around the instrument.
in this manual.
The instrument should not be operated in dusty environments.
Whenever it is likely that safety-protection has been impaired,
the instrument must be made inoperative and be secured against If the CRT filter requires cleaning it can be easily removed by
any unintended operation. Qualified maintenance or repair pressing in its right hand edge as shown by the moulded arrow.
personnel should be informed. Safety protection is likely to be
impaired if, for example the instrument shows visible damage
or fails to perform the intended measurements correctly.
1.1.5 Operating Temperatures
1.1.2 Grounding
The instrument is designed to be operated in an environment
THE INSTRUMENT MUST BE GROUNDED. having an ambient temperature of between 0 and 50 degrees C,
AC (0 to 45 degrees if the battery unit is fitted) and to operate with
The instrument must be operated with a protective ground full accuracy between 15 and 35 degrees C.
connected via the yellow/green conductor of the supply cable. Note: Direct sunlight, radiators and other heat sources
This is connected to the instrument before the line and neutral should be taken into account when assessing the ambient
connections when the supply plug is inserted into the socket on temperature.
the back of the instrument. If the final connection to the supply
is made elsewhere, ensure that the ground connection is made The instrument may occasionally be subjected to temperatures
before line and neutral. between 0 and -10ºC without degradation of its safety.
DC
If the unit is disconnected from the AC supply, and powered 1.1.6 Power and Frequency Requirements
from an isolated DC source or the internal battery unit, the unit The instrument uses less than 85V A (200V A if battery unit
will not be grounded. Independent provision must be made to fitted) and operates from line voltages of 90V to 130V, and
maintain the case at a safe potential, by grounding the safety 190V to 265V, at 45 to 400Hz. Under the extreme conditions of
ground terminal on the DSO rear panel. The safety ground 90V and 45Hz, the instrument will still operate correctly even if
terminal is connected to the instrument case, to the ground of there is a half cycle dropout in the line supply.
the input signals (outer of the BNC connectors), and also
internally to the negative side of the DC supply. The instrument may be powered from a direct current supply in
the range 12V to 33V. The unit cannot be damaged by applying
power to both inputs simultaneously.
WARNING: Any interruption of the protective ground Before connecting the instrument to the supply, ensure that the
conductor inside or outside the instrument is likely to rear panel AC supply voltage selectors are set to the appropriate
make the instrument dangerous. Intentional voltage.
interruption is prohibited. Access to the voltage selector can only be made if the AC
Signal connections to the instrument should be connected after supply connector is removed, and is by hinging open the panel
the ground connection is made and disconnected before the connector from its top edge. The selector barrel can then be
ground connection is removed, i.e. the supply lead must be moved to the required setting. This same operation provides
connected whenever signal leads are connected. access to the AC supply fuse, which must be changed to suit
the supply voltage as shown in table 1.1. 7.
The AC power connection is via a standard IEC, CEE 22
1.1.3 Live Parts connector and the DC power input is via the supplied 0.25"
The instrument should not be operated with covers removed. spade connector (Gould part No. 457839.) See appendix 4 for
The covers protect the user from live parts and polarity details.
400 Operators Manual Getting Started
Figure 1.2a Single Function Buttons
Figure 1.2b The Toggles
Figure 1.2c The Pressure Sensitive Buttons
Getting Started 1.1.7-1.4.1 400 Series Operators Manual
CAUTION: The negative DC terminal is connected to the 1.3 Start-Up Display
safety ground terminal and the instrument case.
Care should be taken to avoid ground loops when,
.
When switched on with the POWER button (1) the instrument
will go through its automatic self-calibration sequence and then
for example, the instrument is used in a vehicle and
display information similar to that shown in Figure 1.3.
powered by that vehicle's supply.
1.1.7 Fuse Requirements
The fuse arrangement shown in table 1.1. 7 must be followed,
and additionally in the UK, a 3A fuse (5A if the battery unit is
fitted) should be fitted in the line supply plug .
Supply Slow Blow Gould Suggested types.
Voltage Fuse Rating Part No Manufacturer/Type No
IEC (ULlCSA) DSO
230V 0.5A (0.6A) 457452 BeswickrrDC488,
Littlefuse/239,
Schurter/FSP
115V lA (1.2A) 457454 BeswickrrDC488,
Littlefuse/239
Schurter/FSP Figure 1.3 Start-Up Display
12VDC 5A (6A) 457979 HRC type
Beswick/S505,
The trace is visible across the centre of the screen. At the top
Wickman 19181
will be the sensitivity of the two input channels and the
BATTERY UNIT
timebase speed. It any input is inactive, information for that
230V lA (1.2A) 457454 BeswickrrDC488, channel will not be displayed.
Littlefuse/239,
Schurter/FSP Users with no previous experience of a DSO will find that the
115V 2A (2.5A) 457455 BeswickrrDC488, 400 responds like a conventional Real Time Oscilloscope while
Littlefuse/239, it is repetitively triggered, but in the absence of further valid
Schurter/FSP triggers, it retains the last trace for continuous display.
Table 1.1.7 Fuse ratings
Note: For different DC voltages, the DC fuse rating multiplied
by the voltage used should equal60W. e.g. at 30V a 2A
fuse is required. For additional safety under extreme 1.4 Obtaining a Trace See Figure 1.4
fault conditions, the DC fuse is a high rupture current
(HRC) type. This fuse should have a 1500A break 1.4.1 AUTO SETUP
capacity.
To display an input signal, connect it via either the CHI socket
()9 or the CH2 socket (12) and press AUTO SETUP (24) .
Assuming you've applied a regular signal, say a 2kHz sine-
wave with an amplitude of perhaps 5V peak to peak, it will
1.2 Using the Buttons see appendix 3 almost immediately be represented on the display. An example
There are three types of buttons. The first type usually have is shown in Figure 1.4.1.
only one function: when pressed, that one function will be It the display is very dim or has completely disappeared see
activated e.g. AUTO SETUP (24). See Figure 1.2a. section 1.8.1.
The second type are toggles: each press of the button either
switches something on or off e.g. Add (10) , or selects the AUTO SETUP will attempt to arrange the display so that two
next item in a sequence e.g. Off/On/lnv (13) . See Figure to five complete cycles appear, with the amplitude set so
1.2b. that the height of the trace is between two and five
The third type are Pressure Sensitive: the effect caused depends screen divisions. Also, it selects Auto trigger to ensure
upon how hard the button is pressed. For example, a gentle that the screen is frequently updated and a trace will be
press of a Pos'n (8) button will move the trace slowly. If the visible.
button is pressed harder, the trace will move more quickly. See
Figure 1.2c. If signals are connected to both channels, the
highest amplitude takes priority.
400 Series Operators Manual Getting Started 1 .4.2-1 .5.1
1.4.3 Coupling (AC/DC/Gnd)(14)
These buttons control the type of coupling between the input signal
and the instrument. DC is the most generally applicable, and
AUTO SETUP will normally set this control to DC, where
possible.
The input impedance is I M ohm in parallel with a capacitance of
28pF.
AC This is used to remove any DC component from input
signals. Suitable input signals (i.e. the bandwidth) are from
4Hz to 20MHz.
Gnd The input signal is internally disconnected from the inputs and
the amplifier grounded. A OV reference signal is displayed.
DC The input signal is directly coupled to the instrument so all
frequency components of the input signal will be displayed.
The bandwidth will be from DC to 20MHz.
Figure 1.4 Obtaining a Trace
1.5 Horizontal Adjustments
Figure 1.4.1 An AUTO SETUP Display
1.4.2 Channel Selection (Off/On/lnv) (13) Figure 1.5 Horizontal Controls
A channel may be switched on or off with its Off/On/Inv button. If
the channel is on, its trace can be displayed in either normal or 1.5.1 TIME/DIVISION
inverted mode.
TIME/DIV (33) These buttons control the sweep rate of the trace.
Off The channel is deactivated. The timebase can be varied from 100ns/div to 50s/div in a I,
On The trace is a true representation of the input signal. Inv The 2, 5 sequence of values. The button marked 'ns' decreases
the time/div, the button marked 'sec' increases the time/div.
input signal is inverted before being displayed. If
there is any DC component in the signal this will also be With a timebase of say 200/Ls, each horizontal screen division
inverted and could cause the trace to disappear from the represents 200/Ls worth of signal. The timebase is shown near the
screen. Such an unwanted DC component can be removed top of the display - e.g. TB=200/Ls.
by selecting AC coupling. Any vertical shift applied to the Assuming a 2kHz signal is applied as mentioned earlier, when the
trace is not inverted. The trigger point remains at the same timebase is set to 500ms/div, an interesting phenomenon may
point on the waveform regardless of inversion. appear: an 'alias'.
Getting Started 1 .5.2-1 .6.3 400 Series Operators Manual
1.5.2 Aliases are 20mV to 50V per division at the probe tip. See Section
3.4.1. If the Uncal light is on, then these buttons vary the
An alias is a false image. The instrument is a digital oscilloscope sensitivity continuously. See Section 1.6.3.
and so takes frequent samples of the input signal in order to update
the trace. Thus, if the signal frequency is higher than the sample
frequency, one sample will be taken from a particular point on the
waveform and the next sample may be taken from a point slightly
further along on a subsequent cycle. It will then display the wave
as being much slower than it really is. See Figure 1.5.2. This effect
is only likely to occur if there are more than 100 cycles of
waveform across the screen.
Figure 1.5.2 Alias Generation
There is a 'Max/Min' glitch detection feature which can be used to
detect aliases. With dot join on, this usually results in a filled-in
wave envelope being seen on the screen, indicating a high
frequency. See Section 3 A.
1.5.3 Position
Position (26) These buttons move all traces to the right or
left.
The position of the cursor (Section 2.4) is fixed in relation to the
1.6.2 Position
trace so it will move with the applied shift. With x-magnified
traces (Section 1.5.4), the cursor can be off the part of the trace
Pos'n (8) These move their respective traces up and down
displayed on the screen. To bring it back into view use the
the display.
CURSOR < > buttons(5) .
If Trace Hold is on (Section 2.2) or a S/Shot capture has been
1.5.4 Magnification
made, any part of the trace which was captured off-screen
Mag (32) Switches horizontal magnification on or off When vertically will be shown by a horizontal line.
switched on, a xl0 expansion is applied to any displayed
trace, which will expand around the centre of screen. The
timebase setting is adjusted to reflect the expansion. 1.6.3 Variable/Uncalibrated
Var (15) When this is set to 'Uncal', the coarse setting of the
attenuator remains unchanged, but a variable attenuation is
The instrument displays 50 dots (samples) per screen division, each applied to the input signal in the range of 1 to 004. Thus,
plotted dot value being obtained from the 512 byte acquisition with an initial setting of IV, the actual sensitivity of the
memory. At an expansion of x 10. there are five dots per division. channel could be set by this control to anywhere between I
V and 2.5V per division. The V/DIV buttons are used to
vary the uncalibrated sensitivity.
1.6 Vertical Adjustments
Each channel has its own set of vertical controls. See Figure 1.6. Example screen display:
CH1 =5V Channel is set to a sensitivity of 5 Volts per screen
division.
1.6.1 VOL TS/DIVISION
V/DIV (11) Adjusts the sensitivity of the instrument over discrete CH2>20mV Channel 2 is uncalibrated and the attenuator is set to a
calibrated ranges from 2m V to 5V per screen division in sensitivity greater than 20m V per screen division.
1,2,5 steps. With a x10 probe the ranges
400 Series Operators Manual Getting Started 1.6.4 - 1.8.5
1.6.4 Add You may need to consult later sections of the manual as not all
Add (10) Displays the sum, or if one channel is inverted the of the operating features have been discussed so far.
difference, of the input signals. The original traces
disappear and the resultant trace is displayed as a 1.8.1 Problem: Traces and Alphanumerics very dim or
Channel 2 trace. completely disappeared.
Intensities too low
1.7 Manually Obtaining a Trace - Press the control button (7) to get the control master
menu, then press numeric button 3 to select the intensity
This subsection describes how to obtain a trace without using
menu. Further presses of numeric button 3 will increase
AUTO SETUP.
the brightness of the alphanumerics on the display. The
You may need to consult later sections of the manual as not all traces can now be intensified using numeric button I.
of the operating features have been discussed so far.
Note:- The display may not become visible until the numeric
button 3 has been pressed several times.
1. When switched on, the instrument will go through its
power-up sequence, checking the internal calibration.
1.8.2 Problem: Trace off the top or bottom of the screen. Too
2. Decide to which channel you are going to apply the
much vertical shift
signal (CH1 or CH2).
- correct with that channel's Pos'n buttons. (8)
3. Make sure the chosen channel is active by setting the
Input has large DC offset
Off/On/lnv (13) for that channel to On.
- AC couple input signal.
4. Set the AC/DC/Gnd button (14) for the chosen chan- - Correct with Pos'n buttons. (8)
nel to Gnd. - Use a less sensitive range.
5. If necessary, turn that channel's Uncal light out by 1.8.3 Problem: Trace not being acquired.
pressing Var once. (15)
Instrument in single capture mode
6. Make sure that horizontal mag is not selected. (32)
- Press Run. (27)
7. Adjust the TIME/DIV setting (33) to give a timebase
Trigger level incorrect
of 5s.
- Select Auto and DC trigger, then adjust the level
8. Set the display Mode (31) to Refr.
control until the trigger level indicator bars are lined up
9. Set the TRIGGER Norm/Auto button (20) to Auto.
with the centre of the trace.
10. Use the CHl/CH2/Ext/Line button (17) to choose the
source for trigger signals. Trigger source on the wrong input
11. Set the trigger coupling with the hf rej/AC/DC button. - Change trigger source. (CH1, CH2, Ext, Line) (17)
(18) Trigger coupling on an unsuitable setting
12. If necessary adjust the position of the trace using the - Change trigger coupling. (hf rej, AC, DC) (18)
Position and Pos'n buttons. (26) & (8)
Trace Hold on
13. Ensure that Trace Hold (25) is not selected.
- Release Trace Hold. (25)
14. Select Run. (27)
Timebase on very slow acquisition
15. Apply the signal through a BNC connector to the chosen
-Adjust TIME/DIV. (33)
CH input socket. (9) or (12)
1.8.4 Problem: Trace is unstable even when triggered.
16. Set the AC/DC/Gnd button (14) for the channel to Alias
either DC or AC, as appropriate. - Check for alias using Max/Min (glitch
17. Adjust the gain of the chosen channel using the V/ DIV detection), and select a faster timebase range.
buttons (11) . For intermediate settings, set Uncal on Noisy input
by pressing the Var button once. (15)
- Select hf rej trigger coupling. (18)
18. Adjust the timebase setting using the TIME/DIV but- - Adjust trigger Level. (22)
tons. (33)
Trigger on Auto
19. If the display is unstable, adjust the trigger Level. (22)
- With low frequency inputs (below 20Hz), Auto trigger
1.8 Operating Hints will initiate triggers overriding the input triggers. Select
Norm trigger. (20)
The following list gives some of the more commonly met
problems in operating digital oscilloscopes, how to correct 1.8.5 Problem: Trace has a very flat top or bottom.
them, and a brief explanation of what was wrong.
Trace captured when off screen vertically and Pos'n shift has
been used
- Use less sensitive V/DIV range when acquiring trace. (11)
- Re-position trace prior to capture.
Advanced Features 2.1-2.1.5 400 Series Operators Manual
Table 2. 1. 1 Useful Frequency Ranges of Coupling
2 Advanced Features
Types
2.1 Trigger Control
Coupling Input
Trigger facilities discussed here are controllable directly from
hfrej 10Hz to 15kHz
the front panel. For the more advanced menu-controlled
facilities see Section 3.4. AC 4Hz to 20M Hz
The power-down trigger setting will be retained on future DC DCt020MHz
power-up.
2.1.2 Level
The trigger level is the threshold at which the instrument will
respond to potential triggers; the trace actually has to pass
through the level indicated for a trigger to be valid. See Section
2.1.3.
The level is indicated on the display by two bars, one on each
side. of the screen, and is adjusted by the level buttons. (22)
For an internal trigger the range is approximately +/- 10
divisions and on external approximately +/ - 3V. If the trigger
signal is AC coupled, the level bars will be offset from the
actual trigger position on the screen by any DC offset present.
2.1.3 Trigger Point (T)
The trigger point is indicated on the display by a 'T' near the
bottom of the screen underneath the trigger. An arrow next to
the T indicates that the trigger point is off the screen.
2.1.4 Slope (+/-)
A trigger is generated when the selected source signal passes
through the chosen trigger level. This transition may be either
on a rising or a falling edge. The rising edge is considered to be
a positive slope and the falling edge a negative slope.
+/- (19)This button selects positive (+) or negative (-)
slope triggers.
Figure 2. 1 Trigger Controls
2.1.5 Trigger Mode (Norm/Auto)
The trigger system operates in either Normal or Auto mode.
2.1.1 Selecting Source and Coupling
In Normal mode, display captures can only occur when a valid
The lowest button in the TRIGGER section of the front panel
trigger input has been received.
selects the source of the trigger.
In Auto mode, if no valid trigger has been received for some
CH1/CH2/Ext/line (17) Steps through the possible sources time the instrument will generate its own trigger and initiate a
of trigger signals. When Ext is selected, the source is the capture. This ensures that the screen is constantly updated
'EXT TRIG' socket (16) in the lower right corner of the irrespective of the input signal. However, if valid input triggers
front panel. are received at a rate of 20Hz or more, the instrument will start
all captures with these triggers and not generate its own.
Selecting line is meaningful only if the instrument is
powered from the mains. Triggering is then from an Auto/Norm (20)This button selects which trigger mode the
internal pulse having a fixed phase relation to the mains instrument is operating in.
voltage waveform. To change this phase relationship, Trig'd (21) This LED lights up when the instrument is
use the trigger delay buttons. See Section 2.1.6. receiving valid trigger signals.
hf rej/AC/DC (18) Steps through the available trigger cou-
pling options; hf rej is a 15kHz low-pass filter ('high
frequency reject'). All the couplings can be used with
any source except Line, with which the input coupling is
not selectable.
400 Series Operators Manual Advanced Features 2.1.6-2.2.1
2.1.6 Trigger Delay 2.2 Capture Facilities
The amount of data which is acquired for display before or The capture facilities allow the traces to be frozen.
after the trigger is determined by the pre or post trigger delay
selected, see figure 2.1.6. The value of this delay is shown in
the bottom right hand of the trace display.
Pretrig This allows a section of the trace that occurred
before the trigger point to be included in the display. The
amount of pre-trigger visible can be set with the front
panel PreTrig/Delay buttons. (23) Pre-trigger can be
set anywhere between 0% and 100% of screen width, in
steps as small as 0.4%.
Trig Delay With this set, the oscilloscope will acquire a trace
following both the specified trigger and a specified
delay. The amount of delay is shown beside the 7 key.
Delay is controlled by the PreTrig/Delay keys. (23)
The size of the steps by which the delay can be
incremented or decremented is controlled by the
TIME/DIV keys, i.e., step size is 0.04 x the time/ div
setting. This can be demonstrated by varying both the Figure 2.2 The Capture Controls
timebase and delay settings, while observing the last two
lines of the Display and Trigger Menu (See section 3.4). 2.2.1 Trace Hold
Once set, the delay time remains the same regardless of There are two ways to freeze the display: a single-shot capture
the selected timebase range. whereby a full trace is acquired then frozen (Section
Figure 3.4a Trace Capture with Delay
Advanced Features 2.2.2-2.4.2 400 Series Operators Manual
2.2.2), or by pressing one of the buttons labelled Trace Hold. socket input to control the Y (vertical) component. It
Trace Hold: (25) Freezes the relevant trace or traces the moment provides an X- Y display of the data captured by the time
they are pressed. A second press releases the trace( s). base and trigger systems. The timebase should be set slow
enough to capture the whole of the signal of interest. This
2.2.2 Single Shot and Run mode is not available with magnified traces (Mag).
These buttons are used to set the instrument into either a capture-
and-freeze mode (S/Shot), or a free running continuous capture 2.4 Cursor Measurements
and re-capture mode (Run).
The instrument allows you to take direct measurements from the
S/Shot (30) Arms the instrument for a single-shot triggered screen display automatically, using inbuilt datum lines and cursor.
acquisition. The Arm'd light will be illuminated to show
that the button has been pressed.
Arm'd (29) Illuminates after the S/Shot button has been pressed;
it will stay lit until either a valid trigger has been received
or until the Run button is pressed.
Stor'd (28) Illuminates on completion of a single-shot
acquisition. This is after the instrument has been Arm'd,
triggered and a complete trace acquired. The light will stay
on until the instrument is re-armed by pressing S/Shot again
or Run is pressed.
Run (27) This button puts the instrument in continuous capture
mode: the instrument will automatically rearm itself after
each capture is completed so that the display will be Figure 2.4 The Cursor and Datum Line Controls
updated with each triggered sweep.
2.2.3 Acquisition Status - AFTS 2.4.1 Cursor and Datum Selection
These characters appear on the screen and can be used with the The cursor and datum lines are switched on or off using the Select
Arm'd and Stor'd lights to determine the 'status of the acquisition Trace button. (4)
in progress. Select Trace (4) Successive presses of this button places the
A Stands for 'Armed'. cursor and datum lines on to the displayed traces in turn. i.e.
channel, channel 2, reference, off, channel etc. If any of the
F Indicates that the acquisition store has been filled with traces are not in use the lines skip to the next valid
enough pre-trigger information to be ready for a fresh selection.
acquisition.
T Stands for 'Triggered': the instrument has received or 2.4.2 The Cursor and Datum Lines
generated a valid trigger; acquisition has begun.
S 'Stored': acquisition is complete. There are three lines, as indicated in Figure 2.4.2. Movement of
them is aCH1eved using the DATUM and CURSOR buttons, as
described below.
2.3 Display Modes
The following three display modes are directly selectable using the
Mode button. (31)
Refreshed The instrument will imitate the style of a conventional
realtime 'scope: the display is plotted from left to right as it
is acquired.
Roll This mode is like a chart recorder: the display scrolls from
right to left until a trace has been acquired. The scrolling
effect is most noticeable on the slower timebase ranges. The
rolling display is frozen by the trigger in S/Shot mode and is
unaffected by trigger in Run.
X-V This mode allows the CH1 socket input to control the X
(horizontal) component of the trace, and the CH2
Figure 2.4.2 The Cursor and Datum lines
400 Series Operators Manual Advanced Features 2.4.3-2.5.5
Dat Selecting this option on the Dat/Pos/Mag button (3) The normal pen sequence is:
allows the position of the datum lines to be controlled
using the DATUM buttons. (2) Pen No. Colour
1 Black
DATUM (2) Used for moving the two datum lines. CURSOR
2 Blue
(5) Moves the cursor to the right and left along the trace. 3 Green
Pos/Mag These selections on the Dat/pos/mag button (3) 4 Red
allow the DATUM buttons to control post storage The pen holder is colour coded with this colour sequence.
position and magnitude. They can only be used with When pens are fitted in this order, trace 1, the border and all the
stored waveforms. Pressing menu button 1 (opposite the alphanumerics are plotted in black, trace 2 in blue, the reference
restore message) will cancel the effect of pos and mag trace in green and the graticule in red. The cursor and datum
on the selected trace i.e. the one with the cursor on it. lines and their measurements are plotted in the same colour as
Pos This option on the Dat/Pos/Mag button (3) allows both the trace to which they relate. The cursor colour also applies to
X and Y shift to be applied to the trace on which the the HPGL output on both the 420 and 450.
cursor is placed, using the POST STORAGE/ DATUM
keys. (2) 2.5.3 Pen Changing
Mag The vertical magnitude of the selected trace can be varied Underneath the plotter lid at the front of the plotter there are
from X4 to XO.062, using the POST STOR- two small blue buttons. The right hand button when viewed
AGE/DATUM keys. (2) The magnification factor is from the front of the OSO is the Pen change button, and the left
displayed near the top centre of the CRT. hand one is the paper advance button.
No horizontal magnification is available using this CAUTION: When changing a pen, extreme care should
control, but x10 magnification may be applied to all be taken not to damage any of the plotter mechanism.
stored traces using the horizontal mag button. See NEVER move the pen carriage by hand.
Section 1.5.4).
To change a pen, ensure that the instrument is switched on and
2.4.3 Making Measurements then proceed as follows:
1. Press the pen change button once. This rotates the pen
The instrument displays, at the bottom of the screen, the time carriage and moves the carriage to the right hand side of
and voltage difference between the intersection of the the plotter.
horizontal and vertical datum lines and the cursor. 2. Gently press the white grooved eject lever towards the
The choice of points between which to make the measurements front of the instrument. The top pen will be ejected from
can influence the accuracy: while the measurements made will the pen carriage and can be removed from the plotter.
always be within the design limits, placement of the cursor at 3. Insert the tip of the new pen into the carriage guide hole.
the desired position is easier at those points where the slope of Gently snap the other end of the pen into place.
the waveform is at its steepest. For example, on a standard sine 4. When the pen has been changed, press the left hand
wave, the most accurate measurements of wavelength are likely button - the paper advance button - and the carriage will
to be made if they are taken between two OV crossing points. move back to the left hand side ready for the next plot.
2.5.4 Paper selection
2.5 Plot Only use Gould paper - Part number 04101165 for a pack of 8
rolls. Other paper types may damage the mechanism.
2.5.1 Internal Colour Plotter Operation
2.5.5 Paper Loading
When the internal colour plotter is fitted to the 400 OSO, plots
CAUTION: When loading paper, extreme care should be taken
of the instrument's display can be sent to it by selecting internal
not to force any of the plotter mechanism. NEVER pull
on the Plot Menu, see section 3.12.
paper through by hand, always use the paper advance
The internal plotter is automatically selected on power up if it button to prevent damage to the plotter mechanism.
is fitted. If required the plot output can be directed via the 1. With scissors, cut the end of the paper square.
RS423 port to an external plotter by selecting RS423 on the
2. Open the plotter cover by depressing the catch and
Plot Menu, see section 3.12.
lifting the cover until it is fully open.
3. Remove the shaft from the paper cradle and if the plotter
2.5.2 Pens
has been used previously remove the plastic or
Only use Gould pens - part number 04101175 for a pack of 4; 1 cardboard tube from the shaft.
of each colour.
Advanced Features 2.5.6-2.5.8 400 Series Operators Manual
4. Insert the shaft through the paper roll and fit the roll into If the plot button is pressed while the plot is in progress, the
the paper cradle. plot will be aborted. Any changes to the instrument status
5. Feed the paper from the top of the roll as shown in during a plot will have no effect on the plot as the data has
figure 2.5.5 below and push it through the slot in the rear already been transferred and stored in the plot buffer.
of the printer mechanism.
6. Press the paper advance button - the left hand blue 2.5.7 External plots
button at the front of the printer assembly - until the A plot of the display can be sent to an external plotter by
paper reappears at the front. pressing the plot button @ . The parameters for the plotter
7. Feed enough paper through to pass through the top and the plot format can be set as described in section 3.7 and
cover, ensure that it is running around the mechanism 3.12.
smoothly and that it is straight.
The display is held while a plot is in progress.
7. Close the plotter cover and ensure that it latches shut.
Plots can be aborted by a second press of the plot button. If the
plot is aborted, the pen will be left in a random position and the
external plotter may need to be reset to restore the pen to its
start position.
2.5.8 Plot positioning and scaling
The output plot from the 400 has the relative positions shown in
figure 2.5.8a. These may be shifted and scaled to position the
plot exactly over a pre-defined grid using the following
procedure with reference to figure 2.5.8b.
The sides of the pre-defined grid are X and Y, the exact
positions of PI and P2 are found by calculating the dimensions
A, B, C and D:
Measure the vertical dimension of the required grid, note
this as Y.
Figure 2.5.5. Paper Loading Measure the horizontal dimension of the required grid,
note this as X.
U sing these values of X and Y, A, B, C and D can be
calculated as follows:
2.5.6 Internal Plotting
When a plot is initiated, the Hold All lamp lights and the
message "PLOTTING - PRESS PLOT TO ABORT" appears
on the screen. After about 9 seconds the hold All lamp goes out
indicating that the data has been transferred to the plot buffer
and that the instrument can be used again. The plotting
message will remain on the screen until the plot is complete Measure and mark the exact positions of PI and P2 from the
when it will disappear. grid edges using figure 2.5.8b and the values obtained above.
In Auto Plot Mode, the instrument is re-armed after the plot The PI and P2 points can now be set on the plotter, refer to the
data has been transferred to the plot buffer, but the front panel plotter manual for details.
controls will remain in-active during plots.
400 Series Operators Manual Advanced Features
Figure 2.5.8a Relative Plot Positions
Figure 2.5.8b Plot Dimensions
Advanced Features 2.6-2.7 400 Series Operators Manual
2.6 Data Transfer For binary transfer, the 400 will cease receiving when the
amount of data indicated by the length field has been received.
Trace data for either CH1, CH2, or the reference trace can be
transferred to and from the 400 oscilloscope and a computer. Unless the selected trace for received data is held or acquisition
is not armed, the selected memory data could be overwritten
There are four I/O commands which are used for the data
almost immediately by a fresh acquisition.
transfer, they are: ST1, STI, ST3, and ST? The first three
commands are used to transfer data and the fourth one to Note: The number base for received data is set by the #X field
interrogate the 400 for its error status. of the incoming string and not by the menu selection. See
section 3.7
2.6.1 Syntax
The strings for the horizontal and vertical ranges must be
To receive the data for trace one, the computer sends "STl". exactly as follows, anything else will result in error status 102
The 400 then responds with: being generated, as will sending 50ns to a 400 or 420.
STl =20m V, 10us, # HdataCRLF
Where #H is: 50s 20s 10s 5s 2s Is 0.5s
0.2s 0.ls 50ms 20ms10ms 5ms 2ms
#H for hexadecimal number base, #0 1ms 0.5ms 0.2ms 0.1ms 50us 20us 10us
for octal number base, 5us 2us 1s 0.5s 0.2s 0.1s 50ns
#B for binary number base, 5V 2V IV O.SY 0.2V 0.1V 50mV
or nothing for decimal number base. 20mV 10mV 5mV 2mV
Data is: the trace information as described below.
CRLF is: carriage return, line feed.
If the 400 receives ST3 and the reference trace is unused, the
2.6.3 Error Status
400 will respond with "ST3=UNUSED" If the 400 receives "ST?", it will respond with a decimal error
status string as follows:
Note: When data is be