WAVI
Waveform Generator Module
Introduction
The WAVl Waveform Generator Module provides one
channel of sine, square or triangle waveform output. The
module is comparable to a standard function generator in
which the adjustment knobs and switches have been replaced by programmable D/A converters and software
switches. The main WAVl functions of frequency, duty
cycle <symmetry), amplitude and DC offset are programmable to 1 part in 4096 ( 12-bit resolution). Output voltage
range is switch-selectable at 1V or 1OV.
The WAVl’s output waveform is available on a standard
BNC connector. The main output as well as T&level
trigger outputs are also available from an on-board screw
terminal block.
Available frequencies cover O.lHz to 2OOKHz in six decade-weighted ranges. Accuracy is typically 5% of setting
(10% on Wz and 20Hz ranges). For optimum accuracy, the
WAVl should be operated in the upper 90% of any given
frequency range. Amplitude accuracy is 5% (to 20V P-I?
into 500 ohms). Peak output current is 2OmA. The WAVl
duty cycle is programmable from 5% to 95%. Sine wave
distortion is typically less than 3%.
DC output and offset function may be used to bias output
waveforms. Alternately, the WAVl may be used as a
general-purpose bipolar bias source of flOV at 2OmA. The
WAVl can also be used to pace the conversion rate of the
AMMlA or AMM.2 modules at rates other than those
provided by the AMM module crystal oscillator.
Hardware Compatibility
TheWAVlcanbeoperatedinslots2through10ofthe500A
or 5OOP mainframe, or in the option slot of the Model 570
or 575. If the WAVl will be used to control an AMM
module via its trigger input, the AMM module must have
PAL revision D or later. If an AMMlA or AMM2 is not
resident in the system, resistor R53 must be installed on the
WAVl to supply a system reference voltage.
Software Compatibility
All WAVl functions can be accessed by writing control
information directly to the WAVl’s slot-dependent Command A (CMDA) and Command B (CMDB) registers.
These functions include frequency, duty cycle, range,
function, amplitude, offset, synchronous stop enable/disable, and global strobe enable/disable.
The WAVl includes a selectable synchronous stop feature.
Synchronous stop allows the waveform output to com-
plete the current output cycle, even though the WAVl
output may have been disabled before this point. Alter-
nately, the WAVl output can be set up to return to 0
immediately when the output is disabled. A waveform
always starts at the lowest amplitude point of the triangle
and sine waves.
Document Number: 501-921-01 Rev. A / 7-90
CopyrightQ 1990 KeithIey Instruments, Inc. Cleveland, OH 44139 (216)248-0400
Control can also be exercised through any high- or lowlevel language which permits writes to memory addresses
(e.g. BASIC POKES). The WAVl registers are write-only.
See the WAVl register map information later in this manual.
If you are using third-party software, be certain that the
software is compatible with the WAVl.
WAVI-1
WAVl
Waveform Generator Module
Figure 1. WAVI Module
Jumper Wl
Optional Resistor R53
Mounting Bracket
Specifications
Programmable Features:
Functions: waveform, frequency, amplitude, duty cycle,
DC offset, haver waveforms.
Waveforms: sine, square, triangle, pulse, or DC output.
Frequency: O.lHz to 2OOkHz in six overlapping ranges.
Frequency ranges: 2,20,200,2k, 2Ok, 200k Hz
Frequency resolution: 12 bits (1 part in 4096)
Frequency accuracy: (upper 90% of range) f5% of setting,
except +lO% on 2kHz and 2OkHz ranges.
Amplitude ranges: IV, IOV peak, switch selectable
Amplitude resolution: 12 bits (1 part in 4096)
,
Amplitude accuracy: rt5% of setting to 5OkHz’
Offset ranges: +lV, +lOV (tied to amplitude ranges)
Offset resolution: 13 bits (12 data + 1 polarity)
Offset accuracy: .(5% of setting + 1OmV)’
Maximum output: rtlOV (2OV p-p) into 5OOQ 2OmA
Waveform symmetry: 5% to 95% (duty cycle) to 1OOkHz
Sine wave distortion: 1st harmonic down 35dB
Square wave rise time: lp
Triangle linearity: ~3% error
* Total error is the sum of amplitude and offset errors. For DC-only
operation, set waveform amplitude to 0 and use offset error, only.
WAVl-2
WAVl
Waveform Generator Module
Sync output: high and low true, TTL level, ps pulse width.
Sync pulse occurs at minima of sine and triangle waves, or
at falling edge of square wave.
General:
Operating temperature: 0°C to 7O”C, 80% RH non-con-
densing down to 35°C
Storage temperature: -25°C to 80°C
Power-up condition: OV output
Rower consumption: 65mA for 5V dig&d, 85rd for +15V
analog
Signal connections: BNC for main output, quick-disconnect screw terminals for main and sync output.
Accessories: 2 ft. BNC to BNC cable, Model 7051-2,3 ft.
BNC to BNC cable, Model 7054-3
--- -.
_--_
ing the cover retaining screws located in the upper corners
of the rear panel. Slide the cover back about one inch and
then lift it off. Insert the module in the desired slot with the
component side facing the system power supply. Replace
the system cover.
For a Model 570, install the module in the option slot with
the component side of the board facing upward. Close and
secure the cover.
For a Model 575, first attach the supplied right-angle
bracket to the module (see Figure 2). Plug the module into
the option dot with the components facing upward, and
secure the bracket to the rear panel of the system. Close and
secure the cover.
Connections
The output waveform is available on a standard BNC
connector or from outputs on a screw terminal block.
Installation
The WAVl can be placed in any slot in the system. If the
trigger output is to be used to control the operation of an
ATiBaI,,TDPI --2--l-
I+IVLIVL ~1 I AU I ~~uuure, ule vv n v 1 muss ue placea aajacenr
to that module, in the next higher-numbered slot.
Turn off power to the data acquisition system
before you insert or remove any module. To
minimize the possibility of EM1 radiation,
always operate the data acquisition system
with the cover in place and properly secured.
Make sure you have discharged any static
charges on your body before handling the
module. You can do this most easily by simply
touching the chassis of a computer or data
acquisition mainframe which is plugged into
a grounded, 3-wire outlet. Avoid touching
components or the card edge connector of the
module.
L~^T*fA~fl----rL--l---=-=~ ----. I
CAUTION
CAUTION
A quick-disconnect terminal block can be removed from
the module to facilitate making connections. PuB the block
straight off the board with a firm, even pressure. Do not pry
the terminals with a screwdriver or sharp object, or you
-_- --- J-.-- - - .I- -? ~~ . . 1~
may aamage me cucun ooara.
Each individual terminal consists of a small metal block
with a wire receptacle containing a metal compression tab.
To make connections to a terminal block, first strip 3/16 of
insulation from the end of the wire which you want to
attach. Loosen the desired terminal screw on the block and
insert the bare end of the wire into the corresponding
receptacle. Tighten the screw securely to compress the tab
against the wire.
After you have attached all the desired signal wires to a
terminal block, replace the block by lining it up with the
mating pins on the module and pressing it back into place.
1
Table 1. WAVl User-Configured Components
For a compatible multi-slot data acquisition system (Model
5OOA, 5OOl?), remove the top cover of the system by loosen-
Cl
WAVI-3
WAVl
Waveform Generator Module
Command Locations
The WAVl is controlled by writing to the Command A
(CMDA) and Command B (CMDB) addresses for the slot in
which the module is mounted. Programmable parameters
include function, range, frequency/duty cycle, amplitude,
and offset. Refer to your data acquisition system hardware
manual for the addresses associated with the slot where the
module is mounted.
Table 2. Slot-Dependent Memory Locations (hex)
1 rigure 3. WAVI Connecfions
NOTE
To minimize the possibility of EMI radiation,
use shielded cable for the WAVl output.
Output Limitations
There are certain restrictions as to the output capability of
the WAVL The output load should be greater than 5OOQ
with less than 100pF of shunt capacitance. The load resistance can be reduced if the peak output current does not
exceed 2OmA (i.e. 1V into 5052).
Jumper WI is provided to enable the user to add a series
resistance to match the characteristic impedance of the
WAVl’s output to that of the cable and load. The addition
of a series resistor can also provide a higher degree of
amplifier output protection. However, the resistance will
increase source impedance and can thus decrease output
amplitude. If the output load capacitance exceeds 1OOpF
(50 ohm coax adds BOpF/foot) Wl should be replaced with
a minimum 1OOQ resistor to prevent output amplifier
stability problems or spurious oscillations.
500,570,575
I I
SLOT
1* xxx80
2
3” xxx84 xxx85
4
5 xxx88 xxx89
6
7 xxx8C xxx8D
8”*
9 xxx90 xxx91
10 xxx92 xxx93
*=Model575 Physical (Option) Slots
**=Model570 Option Slot
xxx=First three digits of IBIN address, e.g. “CFF’
CMDA CMDB
xxx81
xxx82 xxx83
xxx86 xxx87
xxx8A xxx8B
xxx8E xxx8F
GPIB
I I
CMDA CMDB
0 1
2 3
4 5
6 7
8 9
A
C
E F
10 11
12 13
B
D
Table 3. WAVl Command Locations and Functions
Read Functions:
COMMAND
CMDA
CMDB
Write Functions:
FUNCTION
None
None
WAVl-4
COMMAND
CMDA
CMDB
xxx9D
FUNCTION
Select Control Register
Offset Polarity
Data high nibble
Data low byte
Global Strobe
WAVI
Waveform Generator Module
8038 -_I___
Waveform
Generator
2/
AU-L
Waveform
Select
I----
CMDNCMDB
(WRITE)
To ND ‘Module
L
e Data Bus
‘igure 4. WAVI Block Diagram and Register Funcfions
- Control Line
Analog Pathway
WAVl-5
WAVl
Waveform Generator Module
Control I Data
SET FUNCTION :
CMDA
I
D7 D6 D5 C
0 0 0
Register
Select
0
SET RANGE :
CMDA
I
D7 D6 D5 I
0 0 1
Register
Select
1
14 I D3 D2 Dl DO
I I LI-’
L
I
I D2 Di DO
-c F2:: E:i
Data
CMDB (not used)
I
I
D7 D6 D5 D4 D3 D2 Dl Do
Function Select : 00 - DC
Function Select : 01 - Sine
Function Select :
Function Select : 11 - Square
output : 0 - Disable, 1 - Enable
Sync Stop : 0 - Disable, 1 - Enable
Not used
I
D7 D6 I
Range Select
Range Select
Range Select
Range Select : 101 -2Hz
Range Select :
Range Select : 111 -NotUsed
Global Strobe : 0 - Disable, 1 - Enable
Not used
10 - Triangle
CMDB (not used)
x
i D4 D3 D2 Dl DO
- 200 kHz
000
- 20 kHz
001
- 2k Hz
010
-200 Hz
011
-20 Hz
100
110-Notused
I
I
Register Select 2 & 3 - NOT USED
CMDA CMDB (not used)
I
D7 D6 D5
0 1
0 1
WAVZ Block Diagram and Register Funcfions (Cont.)
WAV1-6
0 Register
1 Register
D4 D3 D2 Di DO D7 D6 D5 D4 D3 D2 Dl DO
Select 2 is not
Select 3 is not
I I I
used
used
WAVI
Waveform Generafor Module
Control / Data
SET AMPLITUDE :
CMDA
I
07 D6 D5 D4 D3 D2 Dl DO
Register
Select
’ O O
4
SET OFFSET :
CMDA
I
D7 D6 D5
D4 D3 D2 Dl DO
Data
CMDB
I I
D7 D6 D5 D4 D3 D2 Di DO
CMDB
I I I
D7 D6 D5 D4 D3 D2 Di DO
I
SET OFFSET :
CMDA
I
D7 D6 D5
Regmter
Select
’ -’ O
6
D4 D3 D2 Di DO
WAVZ Block Diagram and Register Functions (Cont.)
CMDB
I I I
D7 D6 D5 D4 D3 02 Dl DO
WAVI-7
WAVl
Waveform Generator Module
Control / Data
SET RAMP-DOWN :
CMDA
I
D7 D6 D5
1 0 0
Register
Select
7
NOTES :
I I I
D4 D3 D2 Dl DO
IV I
D7 D6 D5 D4 D3 D2 Dl DO
Data
CMDB
Ramp-Down LSB
Ramp-Down MSN
Not used
1. The upper 3 bits of the CMDA register select registers within the WAVI .
2. The DAC’s require 12 bits of data, and thus, 2 successive 8-bit writes. The first write must be to
CMDA (MSB), and the second to CMDB (LSB). The CMDA write selects the proper DAC register
pair to be updated. After the CMDB write, the last register select remains in effect until the next
CMDA write operation selects a different register. This allows for faster successive updates of the
DAC LSB last written.
3. The MSB contains 3 bits of register select information and 4 bits of actual DAC data (Most Significant Nibble, or MSN). Data bit D4 is used only for polarity selection as part of offset programming. When D4 is not used, it may be assigned a value of 0 or 1 with the same results. The 3
register select bits, bit D4, and DAC MSN data must be combined before writing to CMDA of the
WAVl . Frequency, amplitude and DC offset functions are controlled by four 1 e-bit DAC’s.
4. The WAVI function, range, output enable/disable, synchronized stop enable/disable and global
strobe enable are controlled by CMDA-only writes. The subsequent CMDB write will have no effect.
CMDAICMDB reads are not supported by the WAVl .
1 NAVl Block Diaqam and Register Functions (Cont.)
WAVI-8
WAVI
Wavefom Generafor Module
Using the WAVI
Typically, the WAVl will be used in conjunction with other
modules in a Keithley data acquisition system. Once programmed, the WAVl will continue to output a waveform
with no additional intervention from the computer. The
full facilities of the computer can thus be used to control
analog and digital I/O. Alternately, the WAVl can be
programmed repetitively within a program to change
frequency, amplitude, waveform type, etc. This permits
complex waveforms to be generated and reproduced each
time the program is run.
To program the WAVI, note the slot in which the module
resides, and write to the corresponding CMDA and CMDB
registers (see Table 4). A complete configuration of the
WAVl requires 10 writes. For subsequent minor changes
such as a new frequency, duty, or amplitude, one or two
writes will generally be sufficient.
In each case, the appropriate bit values DO-D7 must be
chosen and assembled into byte values which are written
to the CMDA and CMDB slot-dependent addresses. The
function of each write is further defined by the WAVl
register select bits (bits 7,6, and 5) written to CMDA.
Before writing any data to the WAVl, set the amplitude
switch on the connector-end of the module for 1V or 1OV
full-scale. The maximum available offset of 1V or 1OV is
also controlled by this switch, and will be the same as the
amplitude.
By using the following sequence of writes, you will be able
to set up the WAVl with the desired operating parameters,
and then switch on the output. Depending on the programming language, these operations can be performed in a
subroutine or subprogram which can be executed each
time a change in the WAVl’s output is desired.
1. Select desired frequency (freq), duty cycle (duty), amplitude (amp), offset (offs), and sync stop mode (ss).
Assign necessary values for function select, range select, sync stop, and enable bits.
rs = range select (0 for 2OOkHz,l for 2OkHz,2 for 2kHz,
3 for 2OOHz, 4 for 2OHz,5 for 2H.z).
mg = range full-scale in Hz (200000,20000,2000,200,20,
or 2).
duty = desired duty cycle in percent (5-95).
amp = desired amplitude in volts (O-10, or 0-lV, depending on setting of the range switch).
offs = desired offset and polarity in volts (-10 to +lO).
ss = sync stop bit (1 for synchronous waveform stop, or
0 for immediate stop).
en = output enable. Will normally be set to 1 to enable
output when the last write is made to CMDA. 0 disables
output.
2. Calculate high byte and low byte for frequency DAC
up/down ramps according to selected range, desired
frequency, and duty cycle.
’ Calculate-ramps:
ramp-up = INT((freq * 2*11- 1) / (rng * (1 - (duty /
1om
ramp-dn = lNT((freq * 2*11- 1) / (mg * (duty / 100)))
’ Test if either ramp > 4095 and recalculate if necessary
IF ramp-up > 4095 OR ramp-dn > 4095 THEN
rng=rng”lO
13% = rs% - 1
GOT0 “calculate_ramps” (beginning of step 2)
and recalculate...
’ Calculate high/low byte values for frequency DACs
ruh = ramp-up \ 256
ml= ramp-up MOD 256
rdh = ramp-dn \ 256
rdl = ramp-dn MOD 256
’ Integer division
‘ Integer division
fs = function select (0 for DC, 1 for sine, 2 for triangle, 3
for square wave.
freq = desired frequency in Hz (0.1 - 200000).
3. Calculate high byte and low byte for amplitude DAC.
bits = (amplitude / F.S. output) * 4095
ah = bits \ 256
al = bits MOD 256
WAVl-9
WAVl
Waveform Generator Module
(F.S. output = 1 or 10, depending on range switch
position.)
4. Calculate high byte and low byte for offset DAC .
bits = tabs. value (offs / F.S. offset)) * 4095
oh=bits\256
01 = bits MOD 256
op = offset polarity (0 for pos, 1 for neg)
(F.S. offset = 1 or 10, depending on range switch position.)
5. Do the POKES
’ POKE high and low bytes to the ramp-down DACs.
’ Register select = 7
POKE cmda, (7 * 32) + rdh
POKE cmdb, rdl
’ POKE high and low bytes to the ramp-up DACs
’ Register select = 6
POKE cmda, (6 * 32) + rub
POKE cmdb, rul
’ POKE high and low bytes to the offset DACs
’ Register select = 5
POKE cmda, (5 * 32) + (op * 16) + oh
POKE cmdb, 01
’ POKE high and low bytes to the amplitude DACs
’ Register select = 4
Frequency and Duty Cycle
The frequency and duty cycle are simultaneously controlled by the values loaded into the frequency ramp-up
and ramp-down DACs for one cycle. The up and down
terminology relates best to the triangle waveform upon
which the sine wave can be superimposed. The duty cycle
parameter can be understood more easily as the positive
portion of a square wave in relation to one complete cycle.
See Figure 5 for waveform relationships. For optimum
accuracy, select the lowest range which accommodates the
desired frequency.
Full-scale for frequency range is obtained by programming
both the “up” and “down” DAC’s with 4095 (FFF hex).
Programming both DACs to the same value will result in
a 50% duty cycle. Some typical frequency DAC values for
50% duty cycle are shown in Table 4.
Table 4. DAC Values and Programming
Equivalents
% of
F.S. Decimal Hex
4095
100
3276
80
2457
60
1638
40
819
20
0
0
Note: For 50% duty cycle, program “w” and “DN” DAC’r
same values.
&HFFF
&HCCC
c&H999
&H666
&H333
&HO00
&HCF
&HCC
&HC9
&HC6
&HC3
&HCO
&HFF
M-ICC
&H99
@I66
c&H33
&HO0
&HEF
&HEC
&HE9
&HE6
&HE3
&HE0
DAC
CMDB
&HFF
&HCC
&H99
&H66
&H33
&HO0
1
POKE cmda, (4 * 32) + ah
POKE cmdb, al
’ POKE range and global strobe values
’ Register select = 1
l?OKEcmda,(1*32)+gs*8+rs
’ POKE sync stop, output enable, and function
’ Register select = 0
POKE cmda, (0 * 32) + (ss * 8) + (en * 4) + fs
The following discussions cover a few of the operating
parameters where necessary details are not immediately
obvious.
WAVl-10
The duty cycle is controlled by the ratio of values written
to the frequency up and frequency down DACs. kogramming both DACs to the same value will result in a 50% duty
cycle since up and down times will be equal.
Note that as a frequency increases toward 100% full-scale,
the range of permissible duty cycles narrows toward 50%.
The duty cycles available for a given frequency and range
can be calculated as follows:
low-duty (%) = 100 * ( freq/rng > / 2
high-duty (%) = 100 - low-duty
At some duty cycles and frequencies, the ramp calculations will produce a ramp-up or ramp-down value greater
WAvl
Wavefom Generator Module
50% Duty 10% Duty
Square
Triangle
Sine
3gure 5. WAVl Wavefom? Phase Relationships
than 4095 counts. If so, it will be necessary to select the next
higher range and recalculate the DAC values to achieve the
desired duty cycle.
90% Duty
will return to the lowest amplitude point in the waveform,
which may or may not be OV.
Amplitude and Offset
To assure that the WAVl output remains off and at OVuntil
fully programmed, the amplitude, offset, and enable bits
should be programmed simultaneously, and after all other
WAVl set-up information has been written to the module.
If the amplitude and offset are programmed while the
enable bit is set to 0, the WAVl’s output will immediately
assume the lowest voltage that results for the given amplitude and offset. Thus, there will be some activity at the
output even before the waveform commences. When the
enable bit is set to 1, the actual waveform will start.
Synchronous Stop Enable/Disable
The synchronous stop bit controls how the WAVl output
waveform terminates. If the synchronous stop bit is set to
0 (disabled), the WAVl output will turn off immediately
when the output enable bit is reset to 0. Note that the output
If the synchronous stop bit is set to 1 (enabled), the waveform will complete the current cycle before switching off.
This means that at lower frequencies, the WAVl output
may continue for several seconds after the output has been
disabled. Again, the output will return to the lowest amplitude point in the waveform, which may not be OV.
The synchronous start/stop feature only applies to sine
and triangle waveforms. A square wave will terminate at
a voltage level somewhere on the falling edge of the
waveform.
Global Strobe Enable/Disable
The global strobe enable/disable bit determines when the
WAVl output will update after new data has been written
to the module. This feature permits several WAVl modules (as well as other analog output modules) to be programmed individually, after which all outputs can be
updated simulatanelously with one write to the system
strobe (address xxx9D).
WAVl-11
WAVI
Waveform Generator Module
The WAVl functions associated with the global strobe are
those functions controlled by D/A converters: amplitude,
frequency, and offset. If the global strobe feature is enabled, the WAVl DAC-related functions will not update
until a global strobe pulse has been issued by the data
acquisition system. If the WAVl global strobe feature is
disabled, any new information will take effect immediately when is written to the WAVl module.
Haversine Pulse
A haversine is a single sine output pulse, e.g. a pulse with
sinusoidal shape which rises from the minimum amplitude point, reaches the maximum amplitude, and decays
back to the
programmed for sine and triangle waves. Programming a
haver square wave can result in the output pulse terminating at any point along the trailing edge of the pulse, rather
than at minimum amplitude.
Haver pulses can be performed by first doing the usual setup writes to WAVl registers 7,6,5,4, and 1 as shown above.
Next, a write must be made to register 0 to simultaneously
set the desired amplitude and turn on the sync stop and
output enable bits. This write should be followed immediately by another write to register 0 which turns off the
output enable bit. Since the sync stop feature is enabled,
one complete pulse should result at the output.
The speeds which can be achieved for haver pulses depend
on the speed of the computer and the speed at which the
output enable and disable writes can be executed. In this
respect, performance improves dramatically under a
compiler language. A 1OMHz 286 computer executing a
compiled (.EXE) file can fire a single haversine pulse at
2ookJsz.
An oscilloscope can be used to examine the ouput of the
WAVl at higher frequencies. If the speed of the language
or computer is insufficient for haver pulses at a given
frequency, multiple pulses will be generated and observed
on the scope.
minimum. WAVl haver pulses should be
offset DAC high and low bytes and polarity). The DC level
will appear at the WAVl output when the output enable bit
is turned on. The frequency and amplitude DACs have no
effect in this mode of operation, and should beset to 0 when
the WAVl is used for DC output.
Notes:
1.
The WAVl specifications are valid only with an AMM
installed in slot 1. If the WAVl is intended for use in a
system that does not contain an AMM, an optional
resistor 5K ohm 0.1% 0X53, included) must be installed.
See the component layout for the location of R53.
2.
The WAVl output signal will contain some spurious
noise. Some of the noise is generated by the mainframe
into which the WAVl is installed, some by the WAVl
itself.
a.
The WAVl generated noise will be at a maximum
with the output amplitude set to a minimum (~1%
of ES.), and the square wave function or synchronous stop functions selected. This noise is caused by
capacitive coupling through the amplitude attenuator DAC. Since it is capacitively coupled, the noise
will be more pronounced at higher programmed
frequencies. Selecting sine, triangle or DC waveforms will reduce the noise.
b.
System-induced noise may be reduced by using a
shielded BNC cable from the WAVl. Any unshielded wires connected to the WAVl can also couple
additional noise onto the output.
C.
A low-pass filter may be added to the input of the
driven device to further reduce the amplitude of
any noise present.
Calibration
This section contains general field calibration information
for the WAVl. The procedures given are not necessarily as
accurate as factory calibration. Also, the procedures given
assume a certain amount of expertise on the part of the
user. If you are not familiar with calibrating equipment, do
not attempt calibration. The procedures in this section
assume that you are familiar with general module operation. Refer to the appropriate manual for details on cali-
brating each module.
Using the WAVI as a DC Bias Source.
The WAVl can be used as a DC bias source with up to
2OmA of output current capability. The DC output function must be selected, and the desired DC level must be
programmed as offset (refer back to programming the
WAVl-12
The WAVl has four calibration adjustments; ramp-up
zero, ramp-up gain, ramp-down zero and ramp-down
gain. The adjustments are somewhat interactive and therefore must be performed in the proper order for calibration
to be achieved.
WAvl
Waveform Generator Module
The ramp zero and gain interact with one another in
addition to the ramp-up zero and gain affecting the rampdown zero and/or gain. The ramp-down adjustments do
not, however, affect the ramp up adjustments.
Required equipment:
4-l/2 digit DVM, accuracy better than 0.1%.
Frequency Counter with pulse period capability.
Environment: 23°C zEPC, less than 35% R.H., non-con-
densing
NOTE
The WAVl specifications are valid only with a
calibrated AMhI installed in slot 1 providing a
VRRF of +lO volts to the WAVl.
Procedure (refer to the component layout Figure 1 for
location of test points and calibration controls).
1. Adjust ramp zero voltage for OV f5mV on TP4 and Tl?5
using Rl?l and RP2.
2. Program the WAVl to output a500Hz square wave, full
scale amplitude, zero DC bias.
3. Connect the frequency counter to the BNC output and
set to measure pulse low width. The square wave is low
during the ramp-up portion of the sine and triangle
waveforms.
4. Adjust ramp-up zero (RPl) for l.OOms kO2ms reading
on the frequency counter.
5. Program the WAVl to output a 2000Hz square wave.
6. Adjust ramp-up gain (Rl?3) for 250~ E$s.
7. Repeat steps 2 through 6 until the readings remain
within specified limits.
8. Program the WAVl to output a5OOHz square wave, fuh
scale amplitude, zero DC bias.
9. Set counter to measure pulse high width.
10. Adjust ramp-down zero (RP2) for l.OOms k02ms read-
ing on the frequency counter.
11. Program the WAVl to output a 2OOOHz square wave.
12. Adjust ramp-down gain (RP4) for 250~ k5~.
13. Repeat steps 8 through 12 until the reading remains
within specified limits.
14. Verify all four calibration points remain within specifications. Repeat entire procedure if necessary to obtain
convergence.
Performance Verification
Required equipment:
4-l/2 digit DIM, accuracy better than 0.1%
Oscilloscope with 2OMHz bandwidth.
MHz frequency counter.
AMMIA or AMM2 in slot 1 supplying reference
Procedure (Global strobe disabled for all tests, 1OV range)
1. Program the WAVl for DC function, output disabled,
2OOKHz range, OHz frequency, OV amplitude and OV
offset. Set the range DC function switch to 10Vposition.
2. Connect DVM and Scope (counter optionally) to main
output.
3. Observe DVM, reading should be less than flOmV.
4. Observe scope, output should be DC with no significant oscillations present.
5. Program +lV offset.
6. Observe DVM, reading should be 1V +_15mV.
7. l?rogram -lV offset.
8. Observe DVM, reading should be -IV fl5mV.
9. Repeat steps 5 through 8 for programmed and observed values of k2, k5, +lOV. Substitute appropriate
errors based on amplitude.
10. Program the WAVl for Triangle function, output enabled, 2OOKHz range, 2OORHz frequency, 1V amplitude and OV offset.
11. Observe scope, output should be a IV peak, 200 KHz
triangle wave. Use the counter to determine whether
the output is within specified limits.
12. Repeat steps 10 and 11 for all full scale frequencies on
the five remaining ranges.
13. Repeat steps 10 through 12 for 2V, 5V and 1OV ampli-
tudes.
14. Repeat steps 10 through 12 for sine and square wave
functions. Random sampling of 10% and 50% of fuh
scale frequencies and amplitudes can be performed to
the testers satisfaction.
15. Program the output for DC function, IV offset.
16. Set range switch to 1V range position.
17. Observe DVM reading .lV rtllmV.
WAVl-I.3
WAVl
Waveform Generator Module
Theory of Operation
WAVl operation involves analog as well as digital cir-
cuitry.
Analog
TheWAVlisbasedonafunctiongeneratorIC,theICL8038.
The IC provides the following facilities necessary for the
operation of the WAVl:
2 switchable current sources
2 comparators for control of current sources
Triangle wave to sine wave conversion
Square wave output
The current sources are varied to control the magnitudes of
their charge and discharge currents. The ramp-up and
ramp-down times, and thus the frequency and duty cycle,
are varied in this way. The ratio of the values of the two
current sources determine the output duty cycle. The current sources are controlled by dual D/A converter U12.
These are two 12-bit DAC’s with their reference inputs
supplied by U19, the 8038. This reference is buffered by
U18B and level shifted referenced to analog ground by
differential amplifier U18A. The reference voltage is essentially divided by the value programmed into each of the
two DAC’s to produce an output current which is subse-
quently converted back into a voltage by amplifiers Ul6A
and U16B. The scaled DAC output voltages are fed to
differential amplifiers U17A and U17B which level shift,
relative to the 8038’s reference output, and feed the current
source control inputs of the 8038.
The 8038 switches the appropriate current source onto the
timing capacitor connected to pin 10. The value of the
capacitor determines the range of available frequencies.
The available values of range capacitors are -1OOOpF to
1OOpF. These values correspond to frequency ranges from
2OOKHz to 2Hz respectively. The group of analog switches
comprised of transistors Q3 through Q16 switch the se-
lected capacitor onto 8038 pin 10.
The three outputs of the ICL8038 are normalized to 3.333
volts peak, buffered and fed to a four line multiplex switch
comprised of U21 and U22B. The triangle output, essen-
tially the capacitor voltage, is impedance buffered by am-
plifier U20B. The sine wave output, having a slightly
reduced amplitude compared to the triangle wave, is buffered and amplified slightly by U20A. The square wave
output is buffered by a complimentary MOSFET amplifier
composed of transistors 421 through 423. A resistor divider composed of R37 through R40 scales the square wave
to 3.333 volts peak.
The mux output is buffered byU24B and fed to DAC U13A.
The output of U13A and I-V conversion amplifier U24A is
proportional to the digital code programmed into U13A
given a 3.333V peak input. The main signal is fed to the
WAVl’s output amplifier U26, which has a gain of 3 or .3
depending on range switch setting, resulting in a maximum output of 1OV or IV peak respectively. DAC Ul3B,
reference selector switch U15A, buffer U25B, and I-V amplifier U25A provide a 10 volt bipolar signal which is
summed into the main signal path with an effective gain of
1 or 0.1, depending on range switch setting, thus biasing
theoutputsignalonaDCvoltageoflOVorlVrespectively.
US, UlO and associated circuitry provide plus and minus
10 volt reference supplies. The output transistors Ql and
Q2 provide additional current driving capability.
Ull and associated circuitry provide a low-true reset pulse
on power-up and down transitions.
U23A one-shot provides a 500ns low-true pulse on every
negative transition of the main square wave output. This
signal is fed exclusively to the system baseboard daisy
chain bus in the direction of slot 1 @MM). U23B one-shot
provides lo& complimentary pulses to the user connector
J2. The PC board is designed to accept a potentiometer and
resistor to allow the user to vary the output pulse width.
Digital
Logic gates Ul, U2 and U3 decode the baseboard control
signals for interfacing with the DAC’s, function and range
select registers. U4 is a transparent latch that holds the
three most significant data bits last selected by a CMDA
write. U5 decodes chip selects from the 3 MSB’s and feeds
them to U6, range register, U7 function register and U8B
offset polarity register. Register U7 contains output enable/disable and synchronous stop enable/disable bits in
addition to function select bits. The remainder of the decoding is done by the DAC internal gating circuitry.
WAVI-14
WAVl
Waveform Generator Module
Troubleshooting
Any observed or suspected problem with a system or
module may be the result of malfunctions in any part of the
system. A hierarchy of possible problem areas is listed
below. The list should help you apply an organized ap-
proach to troubleshooting, starting with software and
working toward a specific module. It assumes that your
system and software have both worked properly in the
past. If you have spares, you can most quickly verify a
system component through simple substitution. Check
your data acquisition system manual or computer documentation
troubleshooting.
1. Faulty software or applications programs - If you have
completed a new program which does not work as
anticipated, review the program design and be certain
that it actually functions as you assume. If a program
which had been running properly begins to behave
erratically, either the supporting software package or
the application program may have been corrupted.
This may occur through disk media failures, power
supply problems, hardware failures, or operator error.
Verify your software package against a back-up copy or
the original diskettes. If the software is questionable,
you should reinstall the software from the original
diskettes or known-good copies. Likewise, your applications program should be restored from backups if a
problem develops. Note that it is crucial to back up
important software and programs. Ideally, you should
make at least two copies, and store one in a location
away from your work site. Application programs should
be backed up regularly as they are being developed.
Printouts of program listings may also be desirable.
2. Faulty computer system - A malfunctioning computer
or peripheral can affect the data acquisition software
and hardware, ranging from minor problems to total
failure. These problems may be continuous or intermittent. If you suspect your computer, remove the data
acquisition interface and run any diagnostics which
came with the system to verify its performance. Also try
running other software with which you are familiar.
Pay close attention for any erratic behavior of the
software which may indicate hardware problems.
3. Defective interface-A malfunctioning data acquisition
interface can prevent the computer from booting up
and operating properly, or it can affect only the data
acquisition system. Some graphics, mouse, and networking adapters conflict with data acquisition interfaces as a result of both using the same addresses or
interrupts. The system operates properly with one of
the cards in place, but diagnostic error messages or
-they may contain additional instructions on
other problems result with both cards plugged in. You
can usually determine incompatibility by trying each
suspected card individually, and then together. Such
incompatibility can often be overcome through switch
settings, configuration changes, or minor modifications to the hardware.
4. Defective data acquisition interface cable - The cable
carries essential power, control, or data signals. Open
conductors in a cable will disrupt the process. Cable
shorts, especially in lines carrying system power supply voltages, may cause a total shutdown of the computer or data acquisition mainframe. If these problems
exist, try disconnecting the interface cable from the
computer and data acquisition system.
There is a maximum permissible length specified for
interface cables. Exceeding the length will also intro-
duce problems. You may note erratic operation of the
computer, corrupt data, or a failme of the indicator
lamps on the data acquisition system to light.
5. Defective data acquisition mainframe - A mainframe
defect can affect any and all data acquisition functions.
Main areas include the mother board logic and connectors, the expansion slots, and the power supply. In the
case of a completely dead acquisition system, always
check any fuses and cabling which carry power.
An individual slot may also be bad. A known good
module can be tried in various slots to determine the
condition of individual mainframe slots.
6. Defective module(s) in general -A failure in a module’s
address, data, or control circuitry can affect other modules if the malfuctions ultimately reach the data acquisition mother board or power supply. You may be able
to locate a faulty module by removing modules individually until the problem clears.
The master A/D module in slot 1 is a special case
because it processes data from alI analog input channels. Any analog input involves its global multiplexer,
programmable gain amplifier, and A/D converter. If
only the analog input functions are faulty, you should
also consider the master A/D module. Use a knowngood A/D module, or first verify your A/D module for
proper operation before troubleshooting another analog module.
Analog output normally relies only on circuitry within
an analog output module unless documentation for the
module states otherwise. The AOM5 modules uses the
IOV precision reference on the AMM module. If you
note inaccurate output levels from the AOM5, the
AMM module may need to be calibrated.
WAVl-15
WAVl
Wavefom Generator Module
Digital input and output are also performed wholly on
a single module, with the exception of the PIMl and
PIM2 power control modules. The PIM modules use an
external board and solid state relays. These should also
be considered in situations where PIM modules are
suspected of being faulty.
In troubleshooting modules, use a software package
with which you are familiar to write a few simple test
programs for the suspected module. Elaborate programs should generally not be used. They may contain
their own errors which mask problems with the hardware.
If a suspected module does not respond as expected,
you may assume that the module requires calibration
or is defective. If a module has no calibratable components, a problem at this point will normally indicate a
failure within the module.
7.
Defective WAV’l module - A WAVl can be checked by
running a few simple programs which test individual
features of the module. The CMDA and CMDB registers can also be exercised to determine correct operation of the module. See information elsewhere in this
manual.
NOTE
The basic accuracy of the WAVl module is 5%.
If a WAV which had been working properly
suddenly becomes inaccurate by more than a
few percent beyond nominal, the problem is
more likely a malfunction and not a calibration
problem. If you cannot calibrate the hardware
after two attempts, you should return it to Keithley for repair or calibration at the factory.
List of Replaceable Parts
This section contains replacement parts information, com-
ponent location drawings and schematic diagrams. Parts
are listed alphanumerically in order of their circuit designations.
Ordering Information
To place an order, or obtain information concerning re-
placement parts, first contact the Keithley customer service
department at (216) 248-0400. When ordering parts, include the following information:
A skilled technician who has access to electronic test
equipment may be able to troubleshoot individual
circuits on a module to isolate the faulty parts. A full
parts list and diagram set are included with each module to aid the technician.
If a defective component is found, replacement parts
may be obtained from Keithley. If factory service is
desired, the module may be returned for repair. All
Keithley-manufactured systems and modules are warranted against defects in material and workmanship
for a period of one year. For information on replacement parts or factory service, see the Parts List section
of the appropriate manual.
1. Model Number
2. Serial Number
3. Part Description
4. Circuit Designation (if applicable)
5. Keithley Part Number
If an additional instruction manual is required, order the
manual package (Keithley Part Number 501-921-00). The
manual package contains an instruction manual and any
applicable addenda.
WAVl-16
Table 5. Parts List - Model WAVl Analog Output Module
WAVY
Wavefom Generator Module
Part No. Quantity Title
C-138-68OP
C-138-68P
c-179-10 3
c-204-1
c-204-10 1
c-224022 2
C-228-100
c-237-1
C-306-.01 1
C-306-l 1
C-365-.01
C-365-l
C-386-270P 1
c-64-1OOP 4
C-64-22F 3
c-64-27P 1
CS-5213 1
cs-547
El-553 6
DZ-75
1
1
1
1
3
2
29
1
1
Cap, 68OpF, 5%, 5OOV, polystyrene
Cap, 68pF, 5%, 5OOV, polystyrene
Cap, lOpF, 20%, 2OV, tantahxn
Cap, 1pF, lo%, 2OV, tantahnn electrolyte
Cap, lOpF, lo%, 2OV, tantalum electrolyte
Cap, .0022pF, 20%, 5OOV, ceramic
Cap, lOOl.tF, lo%, 15V, tantalum
Cap, lj.@, 20%, SOV, ceramic
Cap, .OlpF, lo%, lOOV, polypropylene
Cap, .lj.tF, lo%, lOOV, polypropylene
Cap, .Oli.tF, 20%, SOV, ceramic
Cap, .li.tF, 20%, 5OV, ceramic
Cap, 27OpF, 20%, lOOV, ceramic/ferrite
Cap, lOOpF, lo%, lOOOV, ceramic
Cap, 22pF, lo%, lOOOV, ceramic
Cap, 27pF, lo%, lOOOV, ceramic
Conn, strip, 4 pin QD
Corm, BNC right angle, plastic body
Corm, test point
Diode, zener 15V, lN4744A (TO-41)
Designation
C23
C48, C49, C56
C26
C27
Cl, c2
C28
C5, C6, Cl8
C24
C25
CS, Cl6
c7, c9, ClO, c13, c15, c17, c19,
C32..C45, C46, C47, C5O..C55
C29
c3, c4,00, c31
Cll, c12, C21
c20
g
TPl..TP6
DZl
IC-144
IC-157 2
IC-163
IC-179 1
IC-182
IC-203 2
IC-320
IC-366 1
IC-398 1
IC-504
IC-510 1
IC-558
IC-602
IC-678
IC-686
IC-720
IC-721 1
IC-722 1
J-3
R-176-1.15K
R-176-10K
12
R-176-13.3K
R-263-1.5K
1
IC, dual D-type flip flop, 74LS74 US
IC, quad D fiip flop, 74LS175 US, U7
1
IC, quad 2 input NAND, 74LSO0
u2
IC, quad 2 input NOR, 74LSO2 ul
1
1
IC, decoder/demux, 74LS138 u5
IC, 18V op-amp, 308AW
u9, UlO
IC, spst cmos analog switch, DG211 u21
IC, 4 bit bistable latch, 74LS75 u4
IC, 3-8 line decoder/demulti, 74HCT138 u14
6
IC, dual JFET op-amp, 412
U16..UlS, U20, U24, U25
IC, quad 2-input NOR gate, 74HCT02 u3
1
1
2
1
1
1
2
IC, dual one-shot, 74LS221
U23
IC, supply voltage supervisor, Tl7705AC Ull
IC, dual loading 12 bit DAC, AD7537JN u12, u13
IC, DPDT analog switch, DG423DJ u15
IC, instrumentation amp, AD845JN U26
IC, waveform generator/VCO, ICL8038CCPD
IC, dual 2 to 4 decoder, 74HCT139
u19
U22
Jumper, circuit Wl
Res, l.l5k, .I%, l/SW, metal film
Res, lOk, .l%, l/SW, metal film
R19, R24
R2..R5, RS, R9, R16, R18, R22, R26,
R28, R48
1
1
Res, 13.3k, .l%, l/SW, metal film
Res, 1.5k, .l%, l/lOW, metal film
Rl
R44
WAVl-17
WAvl
Waveform Generator Module
R-263-1lK
R-263-15K
R-263-1K
R-263-20K
R-263-38.6K
R-2633K
R-263-4K
R-263-5.025K
R-263-5K
R-263-9.76K
R-76-100
R-76-10K
R-76-15K
R-76-1K
R-76-22
R-76-2K
R-76-4.7K
R-76-5.1K
R-76-6.8K
R-76-82K
R-88-200K
RF-28
RP-89-1K
RP-89-20K
1
2
1
7
1
1
2
1
4
1
3
3
1
1
2
1
3
1
1
1
2
4
2
2
Res, Ilk, .l%, l/lOW, metal film
Res, 15k, .l%, l/lOW, metal film
Res, lk, .l%, l/lOW, metal film
Res, 2Ok, .l%, l/lOW, metal film
Res, 38.6k, .I%, l/lOW, metal film
Res, 3k, .l%, l/lOW, metal film
Res, 4k, .l%, l/lOW, metal film
Res, 5.025k, .l%, l/lOW, metal film
Res, 5k, .l%, l/lOW, metal film
Res, 9.76k, .l %, 1 /lOW, metal film
Res, 100,5%, 1/4W, composition or film
Res, lOk, 5%,1/4W, composition or film
Res, 15k, 5%, 1/4W, composition or film
Res, lk, 5%, 1/4W, composition or film
Res, 22,5%, 1/4W, composition or film
Res, 2k, 5%, 1/4W, composition or film
Res, 4.7k, 5%, 1/4W, composition or film
Res, 5.lk, 5%, 1/4W, composition or film
Res, 6.8k, 5%, 1/4W, composition or film
Res, 82k, 5%, 1/4W, composition or film
Res, 2OOk, l%, 1 /SW, metal film
Diode, silicon, IN4148 (DO-35)
Pot, lk, lo%, .75W, non-wirewound
Pot, 2Ok, lo%, .75W, non-wirewound
R29
R45, R46
R39
R15, R17, R20, R25, R27, R47, R54
R56
R38
R37,R40
R42
R21, R23, R43, R53
R41
R6, RlO, R34
R7, Rll, R31
R52
R33
R35, R36
R49
R12, R32, R55
R51
R30
R13, R14
D2, D3, D4, D5
Rr3, Rr4
RN, RP2
SW-445
TF-177-1
TF-179-1
TG-192
TG-193
TG-195
TG-47
TG-84
501-921-OOA
1
1
1
1
1
7
3
11
1
Switch (DPDT)
Res net, lk, 2%, 2.25W
Res net, lOk, 2%, 1.3W
Trans, N-channel DMOSFET, VNO104NS(TO-92)
Trans, P-channel DMOSFET, Vl?O104N3(TO-92)
Trans, N than MOSPOW FET, 2N7000 (TO-92)
Trans, NPN silicon, 2N3904 (TO-92)
Trans, l?NP silicon, 2N3906 (TO-921
Manual package
SW1
TF1
TF2
423
422
QlO..Q16
42,417, Q19
QL 43-49, QW Q20, Q21
WAVl-18
-
N
moar-a
2w-’ -*,.. 1
RI
13.3K
r
UIA
..S--.-..
lO.OK
R4
lO.OK lO.OK
R8
lO.OK
S’
C2 lO.OK
I\
2200p c4
lO.OK
R9
*e
TP2
-
&
TPl
TO2
74HCT02
c32 c34
.lUFz,,1UF~~lUF 7~1°F =slUF 5:
c33
.lUF~i1%3?~<1UF ~71°F 75
C36
c37 c39
C38 c40 C42
c41
IUF 7<1UF zl”F -71°F --,l%4F?-
-._
C52 1 C53 1 C54 1 C55 1 C56 1
.lUF T .lUF T .lUF q+ .lUF TIOUFT
1UF -ilUF >ilUF -:lOUF=
c43 c45 c47
c44
C46
C48
J
WE
C WAVI b-256 ::m ;
I
I\
I III
Writing a Custom Driver
for the WAVl Module
The WAVI module is a pro-
grammable source of sine, square
and triangle waves at frequencies of
0.1 to 2OOkHz and duty cycles of 5%
to 95%. A DC offset function permits
the module to be used as a DC bias
source, or to offset the output waveforms relative to 0 volts.
The WAVl can operating autonomously once it has been programmed, leaving more processor
time for performing acquisition,
output, or data management tasks.
Since the module is software-
controlled, any special waveforms,
modulations, etc. can be reproduced
each time the program is executed.
Programming the WAVl is some-
what more involved than other 500series modules because the WAVl
has a greater number of operating
parameters. A complete WAVl setup requires 10 writes, whereas most
other I/O modules need only a few
reads and/or writes. Once the basic
WAVl configuration has been set,
however, a single parameter such as
frequency, amplitude, or duty cycle
can be modified independently. In
this regard, the WAVl is easier to
program than most other modules.
A WAVl can be controlled
completely through BASIC POKE
statements or similar memory-write
functions of other languages. While
this may seem more difficult than
using a high-level command, any
high-level command still needs to
address all the WAVl’s parameters.
Further, controlling the WAVl at a
primitive level offers the following
advantages:
l The WAVl can be operated from
any programming language,
regardless of whether the
language offers specific support
for the WAVl. Soft500, Quick500,
and earlier KDAC500 versions do
not support the WAVl. Users of
these packages might want to add
the WAVl to their systems.
0 The user wiIl have maximum
control over the WAVl. Any prewritten driver for the WAVl may
make certain assumptions or compromises. The WAVl’s extensive
set of configuration parameters
provides many possible methods
of operating the module.
Accessing the WAVl directly at
the hardware level gives the
programmer ultimate real-time
control over the module.
Writing a Custom Driver
for the WAVl Module
l Communication with the WAVl
can be totally customized to the
application. The program may
include prompts, status messages,
and error checking as needed.
A QuickBASIC Driver
for the WAVl
The end of this note provides a
listing for a WAVl driver written in
QuickBASIC V4.5. This is an example of a general-purpose driver
which can access all the WAVl’s
capabilities. It can be used as a subprogram, or compiled and combined
with QuickBASIC’s libraries. The
listing can also be used as a guide to
writing a driver in some other
language. The source code can be
reduced by about one fourth if the
comments are omitted.
A few comments are in order
concerning the driver. First, when
used as a sub-program the driver
must be declared “SUB” in the
beginning of the main QuickBASIC
program. This is accomplished with
the following statement:
DECLARE SUB wavl (add&, sl%,
command.string!J)
.
Table 1. General Usage of the WAVl Driver
DECLARE SUB wavl (add&, sl%, cd$)
CALL wavl(&HCFF8,9, “reset”)
cd$ = “wave=&, freq=lOOO, ampl=5.0, output=on”
CALL wavl (&HCFF8,9, cd$)
WHILE INKEY$=““: WEND
CALL wavl (&HCFF8,9, “reset”)
END
variable, or can consist of the actual
sub-commands enclosed by quotes.
Each sub-command consists of the
parameter type (wave, amplitude,
duty, etc.), followed by an equal sign
and the desired value. Only the first
three letters need to be used for the
type. Multiple sub-commands can be
listed in any order. The general form
for the WAVl command string is as
follows:
Nwave=sin, freq=lOO, ampl=5.0 ,....
output=on”
After the initial module set-up, the
command string can consist of a
single sub-command to program the
new value. In this respect, all the sub
commands are optional, and user
need only reprogram the parameter(s) associated with the desired
change.
The simplest, complete
QuickBASIC WAVl control program
for generating a lkHz, 5V sine wave
using the WAVl driver is shown in
Table 1.
The WAVl driver code must be
added to the program as a “subprogram”. Consult the QuickBASIC
documentation for more information
on writing subprograms.
WAVl Applications
Examples
The use of the WAVl driver is
illustrated in the following applications for mechanical testing, control, and educational uses. The example programs assume that the
IBIN interface is set to segment
address &HCFF8, and that the
WAVl is mounted in slot 9.
This form was chosen to simplify
programming the module. The command syntax includes a parameter
list which passes the system interface address, the WAVl slot, and a
string of operating commands to the
WAVl. The inclusion of address and
slot supports using several WAVls
or mainframes on one computer.
The WAVl driver command
string is a string consisting of all, or
only one of, the sub-commands. The
complete string may be a literal
The command string may also be
entered as “reset”, which will restore
the WAVl to the power-on default
status. Default values are as follows:
Frequency = 1 Hz selected on the
2OOkHz range
Amplitude = 0 volts
output = Off
Waveform = DC
Duty Cycle = 50%
Offset = 0 volts
Stop Mode = Asynchronous stop
Global Strobe = Disabled
Mechanical Test - Since the
WAVl is fully programmable, it can
be used to generate complex waveforms or output patterns which can
be reproduced each time the program is executed. This output must
be fed to other types of amplification
and actuation circuitry. Two examples are compression testing and
shake table control.
Force Actuator liil
Mechanical Test
l Compression Testing
l DC Offset to pre-load the sample
l Haverwave Function for smooth transition point
and avoiding abrupt relaxation of the board
1
Figure 1. Compression Test Set-up
M
Waveform Generator
i-----Et-i
Series 500
Writing a Custom Driver
for the WAVl Module
For compression testing, the
WAVl control registers enable the
module to produce continuous
waveforms, or a single pulse (haver
sine or triangle) anywhere in the
available range of frequency and
duty cycle. This enables a variety of
complex control voltages to be
programmed and applied to an
amplifier and force actuator. The
actuator, in turn, applies a load to a
sample under test. The WAVl’s
offset feature makes it possible to
pm-load the sample under test. A
Model 500A data acquisition system
can house several WAVl modules
and strain gage cards. A fully
integrated, multi-channel system can
thus apply stimuli and monitor
results.
Table 2. Haversine Program for Compression Testing
DECLARE SUB wavl (add&, sl%, cd$)
CALL wavl(&JXFF8,9, “reset/)
cd$ = “wave=DC, offs=-2”
CALL wavl (&HCFF8,9, cd$)
T!=timer: while timer-t!<5: wend
“wave=sin, freq=l, ampl=lO, output=haver”
cd$ =
CALL wavl(&HCFF8,9, cd$)
END
Table 3. Shake Table Control Output
DECLARE SUB wavl (add&, sl%, cd$)
CALL wavl(&HCFF8,9, “reset”)
cd$ =
“wave=square, freq=5, ampl=l, output=on”
CALL wavl &HCFF8,9, cd$)
t!=timerz while timer-t!<lO: wend
amplt=l .o
while amplt <= 5.0
cd$ =
“wave=tri, freq=20, ampl=” + str$(amplt)
CALL wavl(&HCFF8,9, cd$)
t!=timer: while timer-t!<30: wend
amplt=amplt + 0.5
wend
CALL wavl (&HCFF8,9, “reset”)
A program which pre-loads the
drive amplifier with -2.0 volts for
five seconds, and then generates a
1Hz haver sine pulse with 1OV
amplitude is shown in Table 2.
As a shake table controller, the
WAVl can be programmed to output various combinations of waveforms while amplitude, frequency,
or other parameters are modulated
in real time. As in the compression
test example, the WAVl output
must be amplified, and then applied
to a voice coil or other type of actuator. A relatively simple computer
program can call up the various
WAVl waveforms, modulate the
output, control wave durations, time
delays, etc. This example applies the
following test protocol:
1. IV, 5Hz square wave for 10
seconds
2. 2OHz triangle wave with ampli-
tude increasing from 1V to 5V in
.5V steps at the rate of .5V every
30 seconds.
Writing a Custom Driver
for the WAVl Module
Electrical Control - Once pro-
grammed, the WAVl produces a
continuous output until the module
is either reprogrammed or switched
off. Further, one or more parameters
of the WAVl’s output can be modulated under program control. These
features make the WAVl a good
choice for regulating the drive signal
to an electrical load. The parameters
most commonly used for regulation
are amplitude and duty cycle. However, offset alone might be adjusted
where a load requires a continuous,
proportional control voltage.
One example of regulation is the
adjustment of oven temperature.
The system uses a Model 500A with
a thermocouple module for temperature measurements and a WAVl for
control output. The software will use
KDAC5OO/M in conjunction with
the WAVl driver. Since ovens
normally require high current, a
power transistor is used as the
controlling pass element, with the
WAVl supplying drive to the base
of the transistor. To minimize power
dissipation in the transistor, it most
efficient to run the transistor either
saturated or cut off. Thus, a square
wave output from the WAVl is the
best choice.
Regulating the transistor base
drive can be accomplished by either
maintaining the width of the pulses
and changing frequency, or by maintaining frequency and modulating
the relative on and off times for each
pulse. The latter method is simpler
because it requires calculation of
only the duty cycle, versus frequency and duty cycle. One or more
thermocouples can be attached to
the oven to monitor temperatures.
These temperatures are entered into
a control algorithm which calculates
the required duty cycle. and updates
the WAVl.
Educational Applications - Frequently, computerized data
acquisition is taught as part of
engineering courses. The associated
labs usually include many workstations, so finding systems with a
good balance between performance,
versatility, and cost is often a prime
consideration. A Model 575 and
Waveform Generator
WAVl module are a cost-effective
alternative to voltage and current
meters, signal sources, bias supplies,
and other instruments. The system is
ideal for demonstrating basic electrical theory, as well as more complex
aspects of electronics, programming,
and test design.
A single WAVl can operate as a
DC shrce for powering or biasing
low-power circuits (2OmA max. at
up 10 volts). This is ideal for many
types of circuits based on transistors,
FETs, and op-amps. As a source of
square, sine, and triangle waveforms, the WAVl can be used in
studies of RMS, ripple, and load
regulation. The behavior of filter
networks, as well as different types
of inductive and reactive loads, can
also be investigated by combining
the WAVl with analog and digital
I/O facilities of the Model 575.
Multiple analog input channels on
the Model 575 permit many test
points to be monitored at aggregate
speeds of up to 62.5 kHz.
The WAVl module is fuhy compatible with all Keithley 500series
data acquisition systems, permitting
fully integrated excitation and
measurement systems. The performance of test programs will be
highly reproducible because all
stimuli and measurements are controlled under a single programming
environment.
Electrical Tesr
l Oven Temperature Control
l Drive heater with variable rate pulse train. Adjust 1
off time to achieve desired temperature.
l Monitor temperature at various points in the oven
Figure 2. Temperature Regulation with the WAVl
i
c
L--------l
Analog Bus
A/D Converter
AMMlA
i
Series 500
Writing a Custom Driver
for the WAVl Module
Table 4. Controlling Temperature by Modulating Duty of the WAVI Output
DECLARE SUB wavl (add&, sl%, cd$)
CALL wavl(&HcFF8,9, ?eset?
setpoint! = 325 ’ desired temp = 325 deg C
’ WARM-TJl? PHASE - CONTINUOUSLY ON AT 5V OTJTPUT DRIVE
cd$ = “wave=DC, offset=5”
CALL wavl(&HCFF8,9, cd$)
‘Read thermocouple in foreground while temp! < setpoint!
CALL FGREAD(......)
wend
’ REI’GULATION PHASE - HOLD AT SETPOINT
while inkey$=“”
‘Read thermocouple in foreground
CALL FGRFAD(......)
‘Calculate duty based on difference between measured temperature and setpoint. This portion of the program
‘would normally have to be fine-tuned to the appiication. Following equation provides up 95% duty cycle at 20
‘degrees below setpoint
dut! = 5 * (setpoint! - temp)
if dut! > 95 then dut! = 95
if dut! < 5 then dut!=5: outp$=“off’
if dut! => 5 then outp$ = “on”
cd$ = “wave=square, freq=l, ampl=5”
+ “, duty = fi + str$(dut) +
“, output = N + outp$
CALL wavl (&HCFF8,9, cd$)
wend
‘Turn off WAVl and shut down control
CALL wavl(&HCFF8,9, “reset”)
END
Student Lab
l Demonstrate basic electronic circuit
-w
l Digitizes signals at up to 62kHz
l Use software to analyze rms, average ripple and
load regulation
l Use digital I/O to change circuit load
l Variable input frequency to see effects of filter time
constant
Figure 3. Laboratory Workstation Using the Model 575 and a WAVl
-----Model 575
Writing a Custom Driver
for the WAVl Module
’ SUB wavl (add&, sl%, command.string$) STATIC
1 ***********************~*******~*****************************~*************************%****~***~***~****************
’ QuickBASIC Subprogram for controlling the WAVl module.
’ (c) Keithley Instnunents, Inc. 1990 Written in Microsoft QuickBASIC 4.5 - Guy Zumpetta 3/16/90
’ Presumes that the range switch is set to 1OV position. If it is set to 1V position, output and offset amplitude will be
‘0.1 x programed value.
’ Command Syntax:
’ CALL WAVl ( address%, slot%, command-string$ )
’ Where:
’ Address - (long integer) - the segment address of the interface controlling the system containing the WAVl (e.g.
’ &zHCFF8).
’ Slot - (integer) - the slot position of the WAVl (l-10)
’ Command strings:
1
’ INIt, RESet - initialize WAVl to power-up defaults
’ FREquency
’ AMPlitude, LEVel
’ OUTput = Enable, Disable, Haver, or Pulse
’ WAVe = Sine, TRiangle, SQuare, or DC
’ DUTY, CYCle
’ OFFset
’ SYNC, STOpmode
’ GLObal, STRobe = Enable or Disable
’ (Significant characters are capitalized)
’ (Some parameters have other legal aliases - see the code)
’ Include in the beginning of main program:
’ DECLARE SUB WAVl( address&, slot%, command.string$ )
’ Typical usage:
’ CALL WAVl (&HCFF8,9, “wave=sine, ampl=7.5, output=on”)
= 0.1 - 200000 (Hz)
= 0 to 10.0 (volts)
= 5 to 95 or .05 to .95
= -10.000 to +10.000 (volts)
= Sync or Async
POWER-UP
DEFAULT
1 on 2OOkHz
0
Disable
DC
50
0
Async
Disable
’ Up to 8 parameters can be entered as the command.string!§. The parameters must be separated by commas as shown
’ above, but can be entered in any order. If used, INIT or RESET must be used alone. After a RESet, the wave,
’ frequency, amplitude, and enable are the minimum commands to output a waveform. The other parameters wiII
’ remain at defaults.
DEFINT A-Z
STATIC wavt$, freq!, mg&, ampl!, duty%, offs!, outp$, stpm$, strb$
STATIC ss%, en%, fs%, gs%, rs%, ah%, al%
STATIC op%, oh%, ol%, rub%, ml%, rdh%, rdl%
’ Set defaults for the parameters which may not be set through the CALL
13% = 0: mg& = 200000
IFduty%=OTHENduty%=50
IF freq! = 0 THEN freq! = 1: mg& = 200000
’ Parse the command.string$ for the knob(s)
cmd.str$ = LTRIM$(RTRIM$(LCASE$(command.string$)))
DIM wavcmds$(l2)
index% = 0
Writing a Custom Driver
for the WAVl Module
FOR commapt%
IF MID$(cmd.str$, commapt%, 1) = “,” THEN
ENDIF
NEXT commapt%
wavcmds$(index%) = cmd.str$
FOR pass% = 0 TO index%
eqposn% = lNSTR(wavcmds$(pass%), “=“I
op$ = LTR&@(RIGHT$(wavcmds$(pass%), (LEN(wavcmds$(pass%)> - eqposn%)))
knob$ = (LEET$(wavcmds$(pass%), 3))
’ Parse elements in string array “wavcmds$(pass%)” for the operation (Ol?$)
SELECT CASE knob$
= 1 TO LEN(cmd.str$)
wavcmds$(index%) = LEFT$(cmd.str$, commapt% - 1)
and.& = RIGHT$(cmd.str$, LEN(cmd.str$) - commapt%)
cmd.str$ = LTRTM$(RTRlM$(cmd.str$r$))
index% = index% + 1
commapt% = 1
CASE “ini”, ,tres”
fs%=O
ah%=O:al%=O
op%=O:oh%=O:ol%=O
gs%=O:ss%=O:en%=O
ruh%=O:rul%=0:rdh%=O:rdl%=O
duty% = 50
freq! = 1: mg& = 200000
’ LOCATE 25,l: PRINT ‘WAVl STATUS: Initialized and ready”;
GOT0 poke.values
CASE “wav”
wavt$ = LEFT$(op$, 2)
Writing a Custom Driver
for the WAVl Module
SELECT CASE wavt!$
CASE “dc”
fs%=O
CASE “si’
fs%=l
CASE “ix”
fs%=2
CASE “sq”
fS%=3
CASE ELSE
err.flag% =l GOT0 exit.wavl
END SELECT
CASE “fre”
Fl = VAL (op$)
IF f! > 200000 OR f! < .1 THEN err.flag% = 1: GOT0 exit.wavl
Ifduty%<50-f! /mg&ORduty%>lOO-50*f! /mg&THEN
err.flag% = 2
GOT0 exit.wavl
ENDIF
freq! = f!
CASE “dut”, “cyc”
d! =VAL (op$)
if d! , 1 THEN d% = INT(100 * d!) ELSE d% = INT(d!)
IFd%<5ORd%>95THEN
err.flag% = 2
GOT0 exit.wavl
ENDIF
duty% = d%
CASE “amp”, “lev”
a! = VAL (op$)
IFa!<OORa!>lOTHFN
err.flag% = 1
GOT0 exit.wavl
ENDIF
ampl! = a!
bits% = (ampl! / 10) * 4095
ah% = bits% \ 256
al% = bits% MOD 256
CASE “off’
o! = VAL (op$)
IFo!<-lOORo!>lOTHEN
err.flag% =1
GOT0 exit.wavl
ENDIF
op% = 0
offs! = o!
IF offs! < 0 THEN op% = 1: offs! = ABS(offs!)
bits% = (offs! / 10) * 4095
oh% = bits% \ 256
01% = bits% MOD 256
CASE “out”
outp$ = LEF-Mop$, 2)
SELECT CASE outp$
CASE “of”, “di”, “0”
en% = 0
US&- Uon”, “enlf, “1 N
en% = 1
CASE “pu”, “ha”, “2”
en% = 2
ss% = 1
CASE ELSE
err.flag% = 1: GOT0 exit.wavl
END SELECT
Writing a Custom Driver
for the WAVl Module
CASE “sto”, “syn”
CASE “glo”, ‘*&I”
CASE ELSE
END SELECT
NEXT pass%
sfp-4 = LEI=lXop$, 1)
SELECT CASE stpm$
USE Ua,,, “d”, “0”
ss% = 0
&.&E I,$,, “e”, “1”
ss% = 1
CASE ELSE
err.flag% = 1: GOT0 exit.wavl
END SELECT
strb$ = LEFT$(op$, 1)
SELECT CASE strb$
(-ME “d”, “0”
gs%=O
CA% “e”, “1”
gs%=l
CASE ELSE
err.flag% = 1: GOT0 exit.wavl
END SELECT
emflag% = 1: GOT0 exit.wavl
’ Select range bits based on desired input freq
IF freq! <= 200000 THFN rs% = 0: mg& = 200000
IF freq! <= 20000 THEN r-s% = 1: mg& = 20000
IF freq! <= 2000 THEN rs% = 2: mg& = 2000
lJ?freq!<=2OOTHENrs%=3:mg&=200
IFfreq!<=20THENrs%=4:mg&=20
IFfreq!<=2THENrs%=5:mg&=2
Writing a Custom Driver
for the WAVl Module
calc.ramps:
ru.bits& = INTJ(freq! * 2 * 11 - 1) / (m&z * (1 - (dutv% / 100))))
rd.bits& = INT((freq! * 2 A 11 - 1) / (m& * (duty% 1 100)))
’ See if either ramp exceeds 4095 and toggle up one range if necessary
IF (mbits& > 4095 OR rd.bits& > 4095) THEN
mg& = mg& * 10
IS% = rs% - 1
GOT0 calc.ramps
INDIF
’ Check again that the range select and total ramp up/down values are legal
IF r-s% < 0 THEN err.flag% = 3: GOT0 exit.wavl
IF mbits& > 4095 THEN mbits% = 4095: err.flag% = 2
IF rd.bits& > 4095 THEN rd.bits% = 4095: err.flag% = 2
‘Set up the high nibbles and low bytes only if no errors have been detected
rub% = mbits& \ 256
ml% = mbits& MOD 256
rdh% = rd.bits& \ 256
rdl% = rd.bits& MOD 256
poke.values:
‘Set up CMDA and CMDB and POKE out the information
DBF SEG = add&
cmnd.a& = 2 * (~1% - 1)
annd.b& = annd.a& + 1
POKE cmnd.a&, (7 * 32) + rdh%
POKE annd.b&, rdl%
POKE annd.a&, (6 * 32) + rub%
POKE annd.b&, ml%
POKE annd.a&, (5 * 32) + (op% * 16) + oh%
POKE cmnd.b&, 01%
POKE cmnd.a&, (4 * 32) + ah%
POKE cmnd.b&, al%
POKE cmnd.a&, (1% 32) + gs% * 8 + rs%
IFen%=OORen%=lTHEN
POKE cmnd.a&, (0 * 32) + (ss% + 8) + (en% * 4) + fs%
ELSEIF en% = 2 THEN
POKE cmnd.a&, (0 * 32) + (ss% * 8) + (0) + fs%
POKE cmnd.a&, (0 * 32) + (ss% * 8) + (4) + fs%
POKE cmnd.a&, (0 * 32) + (ss% * 8) + (0) + fs%
ENDIF
exit.wavl :
IF err.flag% = 1 THEN
SOUND 1000,l
LOCATE 25,1
PRINT “ERROR 1: WAVl function “‘; wavcmds$(t%); ,,’ is illegal or out of limits
ENDIF
IF err.flag% = 2 THEN
SOUND 1000,l
LOCATE 25,1
PRINT “ERROR 2: Frequency “‘; f!; ,,’ out of limits for duty cycle “‘; duty%; ,,’
ENDIF
Writing a Custom Driver
for the WAVI Module
“;
“;
IF err.flag% = 3 THEN
SOUND 1000,l
LOCATE 25,1
PRINT “ERROR 3: Frequency “‘; freq!; “’ out of limits for duty cycle “‘; duty%; II’
EN-DIF
err.flag% = 0
’ DEF SEG back to 20 (or appropriate value if Keithley software is not used).
ERASE wavcmds$
DEF SEG = 20
ENDSUB
“;
Writing a Custom Driver
for the WAVl Module
Data Acquisition and Control Division
Keithley Instruments, Inc. l 28775 Aurora Road l Cleveland, Ohio 44139 l (216) 248-0400 l Fax: 349-4569
WEST GERMANY:
GREAT BRITAIN: Keithley Instruments, Ltd. l 1 Boulton Road l Reading, Berkshire RG 2 ONL l 0734-861287 l Telex: 847 047 l Fax: 0734-863665
FRANCE
NETHERLANDS: Keithley
SWITZERLAND: Keithley
AUSTRIA: Keithley
ITALY: Keithley Instruments SRL l Viale S. Giignano 4/A l 20146 Milan0 l 024120360 or 02-4156540 l Fax: 02-4121249
Keithley Instruments GmbH l Heiglhofstr. 5 l Miinchen 70 l 089-71002-O l Telex: 52-12160 l Fax: 089-7100259
Instruments SARL 03 All& des Garays0B.P. 60 l 91124 Palatseau/Z.I. * l-6-0115 155 *Telex: 600 933aFax: l-6-0117726
Keithley
Instruments BV* Avelingen West 49 04202 MS Gorinchem*P.O. Box 559.4200 AN Goxinchem*01830-35333eTelex: 24 684 l Fax: 01830-308~.
Instruments SA l Kriesbachstr. 4 l 8600 Diibendorf l 01-821-9444 l Telex: 828 472 0 Fax: 0222-315366
Instruments GesmbH l Rosenhtigelstrasse 12 l A-1120 Vienna l (0222) &) 65 48 l Telex: 131677 l Fax: (0222) 84 35 97
Loading...