AOM5
Analog Output Module
Introduction
The AOM5 is a high-speed analog output module providing four independent channels of D/A conversion. A
system strobe feature, supported by two levels of data
latching in the D/A converter, allows all D/A channels to
be updated simultaneously.
TheAOM5 D/A converters offer 13-bit resolution (12 data
bits plus a sign bit). Four output ranges can be independently selected through software for each channel: lOV, SV,
2V, and 1V. The sign bit switches the converter output
either positive or negative, so the effective full-scale resolution for a bipolar range is 8192 steps. Programming +OV
or -0V results in the same output. Maximum nonlinearity
is fl.O24%.
The AOM5 analog output circuitry has a 5~s settling time,
and can theoretically achieve output update speeds of
2OOkHz. However, the speed of the computer limits the
rate at which successive output values can be written to the
module, with a typical speed being about 6OkHz for a
1OMHz 80286-based computer.
High-speed operation is supported in Keithley’s KDAC500
software by the ANOUTQ (ANalog OUTput Quick) command. The AOM5 analog output circuitry also offers an
“auto-sequence” mode which can be implemented through
PEEK and POKE commands or assembler language. This
feature makes it possible to write optimized high-speed
analog output routines. It is described later in this manual.
HardwareCompatibility
The AOM5 can be operated in slots 2 through 10 of the
5OOA, 5OOl?, or 556 mainframe. Up to nine AOM5 modules
can be used in these systems for a maximum of 36 analog
output channels. The AOM5 can also be used in the option
slot of the Model 570 or 575 for up to 6 analog output
channels.
The AOM5 uses the voltage reference which is a part of the
system A/D converter circuitry. In the 500~series systems
and Mode1575, the reference is located on the AMM analog
master measurement module plugged into slot 1 of the
system. Where analog input measurements are not needed,
an AOM5 can also be plugged into slot 1 of these systems.
This requires that the optional on-board voltage reference
be populated on the AOM5. This reference circuitry is explained later in this manual under the topic “Using the Onboard Voltage Reference”.
Software Compatibility
Keithley’s KDAC500 software fully supports the AOM5. If
you are using third-party software, be certain that the
software is compatible with the AOM5.
The AOM5 can also be programmed by accessing its
command registers. This can be done through any high- or
low-level language by writing directly to the AOM5
Command A (CMDA), Command B (CMDB), and Global
Strobe registers which are explained later in this manual.
Document Number: 501-920-01 Rev. A
Copyright Q1990 Keithley Instruments, Inc., Cleveland, OH 44139 (216)248-0400
AOM5-1
AOM5A
Analog Output Module
3
QQQ 0
B
?gure I. AOM5 Module
Specifications
Channel capacity: 4
Resolution: 13 bits (12 data bits plus polarity bit).
Full-scale Output Ranges: &lOV, &!W, &2V, flV
Output updating: Instantaneous update or global strobe.
Maximum output load: 2wZ minimum. 1OOpF maximum.
Settling time: 5~s to 0.01% flLSB for any step size.
Maximum output update frequency: 2OOkHz
Non-linearity: fl LSB
0
I
CAUTION
Turn off power to the data acquisition system
before you insert or remove any module. To
minimize the possibility of EMI radiation,
always operate the data acquisition system
with the cover in place and properly secured.
CAUTION
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
agrounded,b-wireoutlet.Avoid touchingcomponents or the card edge connector of the
module.
Accuracy:~lOVrange-M.15%‘omV.Otherranges,M.2%
f4mV.
Temperature coefficient: ti.O025% per degree C.
Installation
All features and operating modes of the AOM5 module are
programmable; there areno hardware switches to be set.
AOM5-2
For a compatible multi-slot data acquisition system (e.g.
Model 5OOA, 5OOP, or 556), remove the top cover of the
system by loosening 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.
AOM5
Analog Output Module
For a Model 575, first attach the supplied right-angle
bracket to the module (see Figure 2). Plug the AOM5 into
the option slot with the components facing upward, and
secure the bracket to the rear panel of the system. Close and
secure the cover.
End View
I
Threaded Hole
1
3gure 2. Model 575 Mounting Bracket
Top View
\
,
Connections
The four channels on the AOM5 are accessed through the
quick connect terminals of J2. Each of the four outputs has
two terminal screws: one screw for analog output and one
for analog ground. The channel connections are listed in
Table 1.
the block and insert the bare end of the wire into the corresponding hole. 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 terminalblock by lining it up
with the mating pins on the module and pressing it back
into place.
NOTE
For analog output connections, use shielded
cable to
minimize the possibility of EMI radiation. Connect the shield to module analog
ground. Leave the other end of the shield disconnected.
Output Limitations
The output circuitry of the AOM5 is designed for fast
output settling time.
restrictions as to the output capabilities of each channel.
Generally, there is an upper limit on the amount of capacitance and a lower limit to the resistance that can be connected across the output. To avoid possible oscillation,
output capacitance must be less than 100pF.
Because of the design, there are
Table 1. J2 Connections
Channel
Number
A quick-disconnect terminal block can be removed from
the module to facilitate making connections. Pull the block
straight off the board with a firm, even pressure. Do not pry
the terminals with a screwdriver or sharp object, or you
may damage the circuit board.
Each individual terminal on a terminal block consists of
a small metal block with a hole and metal compression tab
within the hole. 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
If it is necessary to drive a capacitive load larger than
lOOpF, a 1OOzL or larger resistor must be placed in series
with the output. This will slow down the settling time
somewhat, depending on the value of the capacitive load.
A wire jumper is installed on the AOM5 circuit board in
series with each output.
The jumper may be removed and
replaced by a series resistor if desired. The jumpers are
labelled Wl through W4 on the component layout, and
correspond to output channels 0 through 3 respectively.
Similar restrictions apply to the output current, which is
determined largely by the resistive component of the load
connected across the output. If the resistance is too small,
accuracy will suffer. To maintain rated accuracy, the load
resistance should be at least 2w2 at the maximum output of
flOV. Maximum current output is 5mA or less.
If an analog output channel must drive a load with both
low resistance and high capacitance, the output must be
buffered by an external voltage amplifier.
AOM5-3
AOM5A
Analog Output Module
AOM5 Commands and Command Locations
The AOM5 is controlled by writing to the Command A
(CMDA), Command B (CMDB), and Strobe addresses for
the slot in which the module is mounted. Programmable
parameters include selection of channel and range, loading
of data, auto-sequencing control, and strobe. There are no
READ modes for the AOM5. Refer to your data acquisition
system hardware manual for the addresses associated with
the slot where the AOM5 is mounted.
Table 2. Slot-Dependent Memory Locations (hex)
500,570,575 GPIB
I I
SLOT CMDA CMDB
1”
2
3*
4
5
6
7
8**
xxx80 xxx81 0
xxx82 xxx83 2 3
xxx84 xxx85
xxx86 xxx87 6
xxx88 xxx89 8 9
xxx8A xxx8B A
xxx8C xxx8D
xxx8E xxx8F E F
9 XXX90 xxx91
10 xxx92 xxx93
* = Model 575 Physical Slots
** = Model 570 Option Slot
xxx = First three digits of IBIN address, e.g. “ClT
Table 3. AOM5 Command Locations and Functions
Read Functions:
CMDA CMDB
1
4
5
7
B
C
10
12
D
11
13
SLOT-DEPENDENTCMDA,DATAREGISTERSELECT
AND D/A CONTROL
Writing to the Command A location controls the register
selection, auto sequencing, and global strobe updating of
the D/A converter in the analog output circuitry.
D/A control must precede any change in range register
data. This write resets the register auto-sequencing circuit
to the proper register. The lower four bits represent the
register to be written first. Bits D5 and D6 represent the last
channel for auto sequencing of the data written to the
output data registers (registers 0 through 7). Setting bit D7
enables global strobe (see below) to update analog outputs
simultaneously.
SLOT-DEPENDENT.CMDB, D/A DATA AND RANGE
DATA
Through the use of register auto sequencing, the various
D/A control registers can be filled by writing repeatedly to
the CMDB register. Range registers are filled first, in descending order from 3 to 0. After filling the range registers,
the DAC data bytes are written for each channel, LSB first.
The DAC requires two write operations to supply the 13
bits necessary for data and polarity information. The range
registers are only set once, until a write to CMDA points to
the range registers again, and thedata-registers are continuously updated to allow variable output. When the
global strobe update feature is not enabled, the output
channel is automatically updated upon receipt of the second byte of data. When the global strobe update feature is
enabled, data is not latched into the conversion register of
the D/A converter until receipt of the global strobe signal.
Twelve of the available 16 registers are implemented in this
Circuitry.
COMMAND FUNCTION
CMDA None
CMDB None
Write Functions:
COMMAND FUNCTION
CMDA Data register select, D/A Control
CMDB
xxx9D
D/A Data and Range
Strobe (update all outputs)
AOM5-4
Initially, a D/A control is issued which must select one of
the four range registers, register 12,13,14, or 15 for channel
3, 2, 1, or 0 range, respectively. Additionally, the D/A
control must select the last channel for auto sequencing,
and either enable or disable the global strobe update feature.
After the D/A control is issued, the D/A data is loaded.
The command circuitry selects the appropriate range register, and register control is relinquished to the auto-sequencer. The range registers are filled with the proper
range data. The auto sequencer drops to the output data
AOM5
Analog Oufpuf Module
registers. D/A output data is written, and the sequencer
automatically “points to” the next register to be written.
The data is written LSB first, then MSB, going from channel 0 to channel 1, then 2, then 3. If the global strobe update
feature is disabled (in the D/A control word) the output of
the D/A converter is updated immediately upon receipt of
the MSB of data (including the polarity bit). If the strobe
input is enabled, the data is not latched into the output
registers of the D/A converter until receipt of the active
low strobe input.
To determine the digital value corresponding to a given
voltage, it is necessary to know the output range setting of
the DAC. Since the AOM5’s 13-bit converters are organized as 12 data bits plus sign bit, there are actually 4096
possible voltage levels to be programmed, specified with
digital values of O-4095. 13-bit resolution results from
setting the polarity bit for positive or negative output. The
full-scale value is the nominal full-scale value minus 1 LSB,
and the resolution is 1 part in 4096, or about 2.44mV on the
10 volt range. The DAC counts for a particular output can
be calculated as:
COUNTS = ABS [ ( VOLTS / RANGE ) x 4096 I
where counts = DAC data, volts = desired voltage output,
and range = the output range setting for the particular
channel. The digital data must be adjusted to include the
sign bit (the D7 bit in the MSB of the data). This may be
accomplished by adding 128 to the MSB if negative voltage
output is desired.
xxx9D (STROBE)
GLOBAL ANALOG OUTPUT UPDATE!
The strobe command is used to synchronously update all
analog output channels. Thestrobe feature is global, affecting all D/A channels in a system whose global strobe
feature has been enabled. Any analog output whose global
strobe has been enabled, and whose data has not been
changed since the last global strobe was issued, will not
change its output voltage.
Writing to the global strobe command location causes the
STROBE line to go active low, and allows global update of
all DAC outputs if the analog output circuit is so configured.
AOM5-5
AOMSA
Analog Output Module
DATA
CHANNEL 0
CHANNEL 1
CHANNEL 2
CHANNEL 3
MDA. STROBE
(WRITE ONLY) (WRITE ONLY)
CMDS, DATA/RANGE
CMDA (WRITE) D/A CONTROL
D7 D6 D5 D4 D3 D2 Di DO
CMDB (WRITE) D/A DATA OR RANGE
Data Register Format
MSB
D7 D6 D5 D4 D3 D2 Di DO
CHAN 0
CH3OUT-
a
RANGING
2v
IV
J
TO AID
MUX
Last channel for auto-sequencer
Global strobe: Enable (0), Disable (1)
LSB
D7 D6 D5 D4 D3 D2 Dl DO
/ I ’ L :X$+:2 bits
Range Register Format
D7 D6 D5 D4 D3 D2 Dl DO
I
I
‘igure 3. AOM5 Block Diagram and Register Funcfions
AOM5-6
Sign bit: Negative (i), Positive (0)
Range: 1OV (0), 5V (I), 2V (2), 1V (3)
Unused
CMDB WRITE REGISTER TABLE
REGISTER NUMBER
0
1
2
3
DISCRIPTION
Channel 0 LSB
Channel 0 MSB
Channel 1 LSB
Channel 1 MSB
COUNT SEQUENCE
-4-
:
----
+
I
:
----
-b
AOh4.5
Analog Output ModuZe
Last Channel = 0
Last Channel = 1
4
5
6
7
8
9
10
11
12
13
14
15
Channel 2 LSB
Channel 2 MSB
Channel 3 LSB
Channel 3 MSB
Not Used
Not Used
Not Used
Not Used
Channel 3 Range
Channel 2 Range
Channel 1 Range
Channel 0 Range
-+1
-+1
-+1
-+
Last Channel = 2
Last Channel = 3
1
L----b----
SROBE (WRITE) UPDATE OF OUTPUTS, ADDRESS = xxx9D
The GLOBAL STROBE can be used to simultaneously update all D/A outputs in the system. This includes all
output channels on all D/A cards in the system which have been programmed to respond to GLOBAL
STROBE.
To enable the AOM5 to respond to GLOBAL STROBE, write a 1 to bit 7 of the AOM5 CMDA register.
OUTPUT DATA
Calculate the data value (number of bits) for a desired output voltage as follows:
DATA VALUE = (ABSOLUTE VALUE (VOLTAGE) I RANGE) X 4096
Set bit 13 to 0 for positive output, or 1 for negative output. See CMDB for information on writing data to AOM5
data registers.
AOM5 BZock Diagram and Register Functions (Cont.)
AOM5-7
AOMSA
Analog Oufput Module
Automatic Register Sequencing
The AOM5 analog output circuitry includes an automatic
incrementing circuit for the analog output range and data
registers. The incrementing circuitry aids in high-speed
output progr amming. The following information will be
useful for generating analog output by directly accessing
the CMDA and CMDB registers. These operations are
normally handled by KDAC500.
Generally, standard (non-auto sequenced) analog output
is generated by first writing register select information to
CMDA, followed by writing the corresponding data to
CMDB. These steps are repeated until all the necessary
range and output data have been written for a desired
channel. For channel 0, a typical sequence might be as follows:
1. Write “15” to CMDA to select the channel 0 range
register.
2. Write the desired range to CMDB.
3. Write “0” to CMDA to indicate that the following data
will be analog output low-order byte for channel 0.
4. Write the channel 0 low-order data byte to CMDB.
5. Write “1” to CMDA to indicate that the following data
will be analog output high-order byte for channel 0.
6. Write the channel 0 high-order data byte to CMDB.
(Note that bit D7 governs the polarity of the output.)
7. Write to the GLOBAL STROBE location (xxx9D) to update the channel 0 output.
Table 4. AOM5 Automatic Sequencing
Zegister
VO.
0
:
3
4
ii
7
12
?I
15
Description Sequence
Channel 0 LSB data
Channel 0 hEB data
Channel 1 LSB data
Channel 1 MSB data
Channel 2 LSB data
Channel 2 MSB data
Channel 3 LSB data
Channel 3 MB data
Channel 3 range
Channel 2 range
Channel 1 range
Channel 0 range
1
i
Note that entry points in the loop may be range information or output data. As an example, if the initial write to
CMDA is “14”, the analog output circuitry would assume
that the next byte is the channel 1 range, followed by the
channel 0 range, the channel 0 least significant data byte,
the channel 0 most significant data byte, and so on. Once
the sequence moves out of the range registers, it will cycle
continuously through the channel registers without returning to registers 12 through 15.
Automatic register sequencing automates several of the
write operations listed above. It first requires that a control
byte be written to CMDA (see Tables 2,3, and 4). This byte
must include the register selection and last channel desired
for auto sequencing. The most significant bit (MSB) of the
byte must be 1 to disable the global strobe function.
Next, data must be written to CMDB. This data may be
range data or the output low-order or high-order data byte,
according to the information written to CMDA. The information written to CMDA also sets the “entry point” in the
auto-sequencing loop, thus establishing the expected order of subsequent bytes written to CMDB. The auto sequence logic assumes that the next bytes will conform to
the following sequence:
AOM5-8
If the first control byte written to CMDA is 0 through 7, the
auto sequence logic will expect that the next bytes written
to CMDB will be data. The loop will not enter the range se-
lection registers at all.
If the first control byte written to CMDA specifies that
channel 0 is the last channel for auto sequencing, then the
loop will run only through registers 0 and 1 (channel 0 LSB
and MSB data) and not include registers 2 through 7. This
path will confine output to channel 0 and permit the maximum output speed from channel 0.
The GLOBAL STROBE is typically disabled for auto se-
quencing. This enables the output of a channel to be up-
dated as soon as the MSB data for the channel is written to
the channel MSB register.
AOM5
Analog Output Module
Calibration
This section contains general field calibration information
for the AOM5. 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 calibrating each module.
The only calibration necessary on the AOM5 is to adjust the
+lO and -10 volt reference voltage buffer amplifiers. The
voltage reference used by the AOM5 is the system +lO volt
reference, which is typically provided by the AMM2 or
AMMlA A/D converter modules. The output voltage
accuracy of the AOM5 is affected by the accuracy of this
reference, so it may be desirable to calibrate the AMM2 or
AMMlA module first.
The calibration of the AOM5 proceeds as follows:
Using the same reference voltage for generating and metering test voltages also has error canceling advantages.
For example, if the reference voltage is slightly off, both the
output voltage to an experiment and the resulting voltage
reading by the A/D will both be off by the same percentage
including the polarity of the error. Calculations which ratio
the drive voltage to the measured voltage will cancel the
error terms due to inaccurate reference voltage, and result
in a more accurate experiment result. The system reference
must be used where it is present, i.e. when an A/D module
is in the system.
For cases where no A/D is used in the system, a reference
voltage must be provided to the AOM5 for proper operation. The user may install components Ul, RI, R2, and R3
on the AOM5 to generate a +lO volt reference. If more than
one AOM5 is to be installed into a system, only one AOM5
needs these parts installed. This one reference circuit will
provide the 10 volt reference for any other AOM5 in the
system. These parts must be removed if an A/D module is
later installed in the system, since the two references will
conflict.
1. Measure the 10 volt system reference on the AMM2 or
AMMl A by attaching the voltmeter (+) lead to TI’7, and
the voltmeter (-) lead to the analog ground test point
TP4. Note this voltage reading for use later.
2. Connect the voltmeter (+) lead to TPl on the AOM5, and
the (-) lead to TP2 on the AOM5. Adjust pot R12 for a
voltmeter reading identical to the reading obtained in
step 1.
3. Connect the voltmeter (-)lead toTIYpntheAOM5, and
the (+> lead to TP3 on the AOM5. Adjust pot R13 for a
voltmeter reading identical to the reading obtained in
step 1.
Please note that R12 must be adjusted first, as it affects both
the voltage at TP2 and TP3.
Using the On-board Voltage Reference
The AOM5 is supplied from the factory without a built-in
voltage reference because the AOM5 is typically used in a
system containing either an AMMlA or AMM2 A/D
converter module. The AMMlA and AMM2 provide a
very high quality reference voltage to the system, so anonboard AOM5 reference is unnecessary.
These parts may be ordered from Keithley Instruments
Repair Department by requesting the following Keithley
part numbers (see Table 5):
Table 5. Components, On-board Voltage Reference
Keithley
Des&.
Ul
RI
R2
R3
Part No. Description
IC-677 IC, TL431CL.P Adjustment
Shunt Regulator
R-76-1K
R-263-6K
R-263-2K
Resistor
Resistor
Resistor
Theory of Operation
Refer to schematic drawing 501-236 for the following discussion:
Each of the four outputs function identically, and only the
channel 0 output part references to the schematic are
included below.
second sheet of the schematic drawing is described first.
The analog portion of the circuitry on the
AOM5-9
AOM5A
Analog Output Module
The development of a specific output voltage begins with
the selection of either the +lO volt or -10 volt reference
voltage by the analog switch U19. If a positive output
voltage is desired, the -10 volt reference voltage is used,
and vice versa. U19A is turned on by a low logic level on its
pin 1 when a negative output voltage is desired, and U19D
is turned on by a low logic level on its pin 8 when a positive
output voltage is desired. The selected reference voltage is
buffered by amplifier U31A and fed into the reference
input of the multiplying D/A converter U21. The multiplying D/A converter functions by multiplying the 10 volt
reference input by the digital number programmed by the
computer. The digital value programmed represents a
number between 0 and 0.99976. Amplifier U27A is part of
the multiplying circuit, and the overall output of the multiplying D/A converter circuit is at pin 1 of U27A. The
voltage at this point always has a span of 0 to +9.9976 or 0
to -9.9976 volts. The resistor divider formed by R19, R23,
R27, and R31 and analog switches U23A through U23D
form the range selection circuitry. One of the four analog
switches is on at a time, and selects a tap on the resistor
divider which divides the output of U27A by 1,2,5, or 10.
This results in a span of 0 to 10,5,2 or 1 volts, respectively,
at the input of U28A, the output amplifier. Capacitor C8,
combined with the voltage divider impedance and R35,
R39, and R43, provides filtering for the signal to help
remove glitches when the D/A converter output voltage is
changed. The output of U28A drives the output connector
directly. A wire jumper, Wl, on the circuit board provides
alocationforconnectingaresistorinseries with theoutput,
if needed.
The command decoding circuitry is on sheet 1 of the
schematic. U5 buffers some of the data and control lines to
prevent excessive bus loading. The output of the 4-bit
counter U8 represents the number of the control register
which will be used on the next data write to CMDB. The
output of U8 is decoded into the various write enable
pulses for the data latches of the schematic by U6 and UlO.
When data is written to CMDA, bits DO, 1,2, and 3 load the
counter U8 and bits D4,5,6, and 7 are stored in U7. Every
time a write is performed to CMDB, magnitude compara-
tor U9 compares the output of counter U8 with the data
previously latched into D5 and D6 of U7 to determine if the
last register has been filled. If a match is determined, the
output of U9 causes the counter U8 to be cleared, thus
resetting the CMDB register pointer to the Channel 0 LSB
register. This reset occurs at the conclusion of the CMDB
write pulse.
Components Ul, Rl, R2, and R3 are not installed at the
factory, and are normally not needed. Please refer to the
section of this manual, “using the Onboard Voltage Reference”.
Calibration of the analog output circuit is not necessary
other than the calibration of the +lO volt and HO volt
reference voltages (described in the AOM5 calibration
procedure).
Troubleshooting
The +lO and -10 volt references for all four output channels
come from a common set of reference amplifiers, U2 and
U3. Refer to sheet 1 of the schematic. The 10 volt systemreference(lOVRBF),andsystemgroundreference (AN_COM)
come from the system baseboard on Jl, and go to a differential amplifier circuit comprised of U2, R4, R5, R6, R7,10,
and Rl2. This amplifier inverts the reference voltage to
provide the AOM5 -10 volt reference, and isolates the
baseboard AN-COM ground reference from the AOM5
output ground reference. C24 provides a low AC output
impedance. Components C2, C26, and R48 stabilize the
feedback loop around U2. An inverting amplifier comprised of U3, C3, C25, C27, R8, R9, Rl 1, R13, and R49 makes
the +lO volt reference signal.
A power-up reset circuit made up of U4 and the associated
components resets all the bits in the D/A converter registers to 0 when the power is first applied, which results in an
output of 0 volts on all channels.
AOM5-10
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 approach 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 - they may contain additional instructions on
troubleshooting.
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 pro-
AOM5
Analog Output Module
gram 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.
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.
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 other problems result with both cards
plugged in. You can usually determine incompatibility by
tryingeachsuspected card individually, and then together.
Such incompatibility can often be overcome through switch
settings, configuration changes, or minor modifications to
the hardware.
Defective data acquisition interface cable -The cable carries essential power, control, or data signals. Open conduc-
tors 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 introduce 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.
Defective data acquisition mainframe -A mainframe defect can affect any and all data acquisition functions. Main
areas include the motherboard 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.
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
motherboard 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 all 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 known-good 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
analogoutputmoduleunlessdocumentationforthemodule
states otherwise. The AOM5 modules uses the 1OV precision reference on the AMM module. If you note inaccurate
output levels from the AOM5, the AMM module may need
to be calibrated. Digital input and output are also performed wholly on a single module, with the exception of
the PlMl and PIM2 power control modules. The PIM
modules use an external board and solid state relays. These
should also be considered in situations where PlM mod-
ules 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
AOM5-11
AOM5A
Analog Output Module
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.
c
Defective AOM5 module - An AOM5 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.
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.
List of Replaceable Parts
Table 6 contains replacement parts information. Parts are
listed alphanumerically in order of their circuit designations. A component location drawing and schematic dia-
gram for the AOM5 are found at the end of the manual.
Ordering Information
To place an order, or obtain information concerning re-
placement parts, first contact the Keithley customer service
department: (216) 248-0400. When ordering parts, include
the following information:
1. Model Number
2. Serial Number
3. Part Description
4. Circuit Designafion (if applicable)
5. Keithley Part Number
If an additional instruction manual is required, order the
manual package (Keithley Part Number 501-920-00 Rev *).
The manual package contains an instruction manual and
any applicable addenda.
NOTE
If a calibratable module which had been working accurately suddenly becomes inaccurate by
more than a few percent, 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.
AOM5-12
Table 6. Parts List - Model AOM5 Analog Output Module
AOM5
Analog Output Module
Part No. Quantitv
C-365-.1
c-64-1ooP 4
C-64-22P
CS-521-4
CS-553
IC-173
IC-182
IC-186
IC-190
IC-203
IC-215
IC-246
IC-267
IC-272
IC320
IC-366
IC-389
IC-504
IC-678
IC-724
14
8 Cap, 22pF, lo%, lOOOV, Ceramic
1 Corm, Strip, 8 Pin
3 Corm, Test Point
1 IC, Voltage Comparator, LM311N
1 IC, Decoder/Demux, 74LS138
2 IC, Hex Inverter, 74LSO4
3 IC, 2 to 4 Line Decoder/Demux,
2 IC, 18V OP-Amp, 308AN
1 IC, Quad 2 Input Pos AND, 74LSO8
2 IC, 18V O&Amp, 353
1 IC, 8 Ch CMOS Analog Multi, 6108
1 IC, 4Bit Counter, 74LS163A
6 IC, SPST CMOS Analog Switch, DG211
5 IC, 4 Bit Bistable Latch, 74LS75
1 IC, 4BIT Magnitude Comparators, 74LS85
4 IC, Dual JFET O&Amp, 412
2
1
Title
Cap, .luF, 20%, 5OV, Ceramic
lOOpF, lo%, lOOOV, Ceramic
IC, 12-Bit DAC, AD7537JN
AOM5 PAL, MME!OLlO
Designation
Cl, C12...C25
C2, C3, C27, C28
C4...Cll
J2
Tl?l...Tl?3
u4
UlO
u13, u15
74LS139 U17, U18
u2, u3
u5
U31, U32
U33
U8
U19, U20, U23...U26
u7, Ull, u12, u14,
u9
U27...U30
u21, u22
U6
J-3
R-176-10.7K
R-263-1OK 10
R-263-2K 8
R-263-6K 4
R-76-39K 1
R-76-4.7K 1
R-76-47OK 1
R-88-l .82K 4
R-88-22.1 2
R-88-3.16K 4
R-88-37.4K 1
R-884.99K 5
R-88-470 2
RF-28
RF-89-200
MC-334
501-920-00
4 Jumper, Circuit
1
1 Diode, Silicon, lN4148 0X-35)
2 Pot, 200,10%, .75W, Non-Wirewound
1
1 Manual Package
Wl...W4
Res, 10.7K, .l%, 1/8W, Metal Film, T2
Res, lOK, .l%, 1 /lOW, Metal Film
Res, UC, .l%, l/lOW, Metal Film
Res, 6K, .l%, l/lOW, Metal Film
Res, 39K, 5%, 1/4W, Composition or Film
Res, 4.7K, 5%, 1/4W, Composition or Film R18
Res, 47OK, 5%, 1/4W, Composition or Film
Res, 1.82K, I%, 1/8W, Metal Film
Res, 22.1,1%, 1/8W, Metal Fihn
Res, 3.16K, l%, 1/8W, Metal Film
Res, 37.4K, l%, 1/8W, Metal Film
Res, 4.99K, l%, 1 /SW, Metal Film
Res, 470,1%, 1/8W, Metal Film
Warning Label
R47
R4...R9, R19...R22
R27...R34
R23...R26
R14
R17
R39...R42
RlO, Rll
R43...R46
R15
R16, R35...R38
R48, R49
Dl
R12, R13
AOM5-13
lJ1 ,F?l,FQ,R3 TO BE USER INSTALLED
-/
I I
I
I
I /
/
I
Using the AOM5 Module
with KDAC500
The following notes describe
general techniques for using the
AOM5 Analog Output Module. The
AOM5 will normally be used to
apply a voltage to some other
electrical, electronic, or electromechanical device. Typical uses
include biasing, excitation, or
driving equipment whose function,
position, or other performance parameters change in response to a
control voltage.
The supplied program examples
for these applications are oriented
around BASIC and the foreground/
background output commands in
Keithley’s KDAC5OO/I software. A
foreground output command writes
a single value, previously stored as a
variable, to a chosen AOM5 channel.
A background output command
sequentially writes the elements of a
memory-resident KDAC500 array to
the desired channel at a rate set by
KDAC5OO’s programmable
interrupts.
The channel input/output names
(IONAMEs) must be set up in the
KDAC500 hardware configuration
(CONFIG) table according to the
AOM5’s slot position and the channel being used. The AOM5 output
channel name used in the example
programs is “OUTCHAN”. Likewise, the analog input channel name
used in Example 4 is “LNCHAN”.
If you are using another software
package, consult your software
documentation for operating modes
and commands. In most programming languages, it is also possible to
get the equivalent of foreground
commands by writing directly to the
AOM5 CMDA, CMDB, and STROBE
command registers.
Output Current
Compliance
The AOM5 has a maximum output
drive current of five milliamperes.
Where an application requires
greater drive power, connect the
AOM5 output to a suitable current
amplifier or programmable analog
power supply. In this case, the
AOM5 drives the amplifier, which
drives the load.
DAC
Using the AOM5 Module
with KDAC500
V Out with
greater current
capability
I
AOM5 Module
Figure 1. Boosting Drive Current
Initializing the AOM5
The AOM5 outputs will automatically initialize to 0 volts when a
system containing the module is
switched on. The KDAC500
HARDINIT utility, which can be
executed through the computer’s
AUTOEXEC.BAT file, is not
required to initialize the AOM5 at
power-up. However, HARDINJT
may be used to initialize other
digital or analog output modules
that lack a power-on reset.
060
Programmable analog
voltage is programmed, or until the
system
commands may be executed earlier
or later in the program without
affecting the AOM5 output level.
Note that where the desired
output voltage does not fall exactly
on a bit boundary, the actual output
voltage will be a maximum of 1 D/A
bit lower than programmed. For
instance, programming 6.43V will
result in 6.428V.
0.0
A
v out
power supply
is reinitialized. Other I/O
Ramped Output
Output ramps can be programmed by using the background
output (BGWRITE) command to
write a KDAC500 array to the desired AOM5 channel.
First, the ARMAKE must be used
to allocate the array. A FOR-NEXT
loop is then set up to:
(a) linearly increment a data value
and an array position index,
fb) place the data into the
KDAC500 array at the correspond-
ing index with ARKJT,
(c) repeat until the array is full.
The loop may also apply scaling
or offset calculations to the data to
achieve a desired offset and slope for
the ramp. Further, the data values
may be calculated as voltage, current, percent of full scale, or raw
D/A counts so long as the appropriate engineering unit flag is used
in ARFUT. The maximum resolution
The KDAC500 command KDINIT
will return all AOM5 outputs to 0
volts anytime it is called within a
program. This is an easy method for
resetting all analog and digital
outputs to 0 immediately before
terminating a program.
Programming a
Continuous Voltage
Many applications will require the
AOM5 to be programmed and held
at a specific voltage level while other
tests are conducted. This may be
accomplished most easily by
executing a foreground output
(FGWRlTE) command. After the
foreground write, the AOM5 output
will remain constant until another
10
‘ Program 6.43V output with foreground write
20
’ Set AOM5 for +/-1OV range
30 CALLKDINIT
:
: (BASIC and/or KDAC500 commands)
400 dIM VOuT!(l)
410 VOUT!(O)=6.43
420 CALL FGWRITE’(“outchan”, vout!(), “c.volts”, “nt”)
: (BASIC and/or KDAC500 commands)
900 CALLKDINrr
1OOOEND
Example 1. KDAC500/1 Foreground Write
Using the AOM5 Module
with KDAC500
the AOM5 is 8192 steps for any bipolar output range. Careful selection
of AOM5 range wiI.I provide optimum resolution for any output
signal.
After the array has been created, a
BGWRITE command must be set up
for the desired AOM5 channel. Anv
other background commands shoid
also be inserted at this point in the
program.
10 ’ Output a ramp from 0-1OV in 4.096 set
20 CALLKDINIT
: (BASIC and/or KDAC500 commands)
:
100 CALL ARMAKE’f”outarray%“,
110 DIM BITVAL%(l)
120 ’
130 FOR D!=l TO 4096!
140 BITVAL%(O)=D!
150 CALL ARPUT’(“outarray%“, D!, D!, “outchan”, 1, bitvaI%O,
“c.raw.intY)
160 NEXTD!
.
I (BASIC and/or KDAC500 commands)
:
200 CALL BGWRITE’(“outarray%“,
210 *
220 CALL INTON’(l,“miI”)
230 I
240 STAT%=-1
250 CALL BGSTATUS’(“done”, stat%)
260 IF STAT%<>0 GOT0 250
270 CALL INTOFF
: (BASIC and/or KDAC500 commands)
900 CALLKDINIT
1OOOEND
Example 2. Ramp with KDAC500/1 Background Write
To write the array to the AOM5,
set up an INTON command, being
carefuI that the specified interrupt
interval is adequate for the computer
type and number of background
tasks. When the program runs, the
output ramp wiB begin when the
INTON command is executed. The
BGWRITE command may be given a
cycling parameter for continuous
output or n repeats.
4096., “outchan”)
“outchan”, 1, 1, “nt”,
“done”)
Output of Periodic or
Complex Waveforms
Periodic and complex waveforms
are handled in a fashion similar to
ramps, except that the FOR-NEXT
loop contains a mathematical
equation to calculate the output
data. The equation may be linear or
non-linear in order to generate
ramps, curves, periodic waves,
random patterns, or combinations
thereof. Synthesizing a single cycle
of the wave form is usually
adequate. The BGWRITE command
cycling parameter can be set to
output a specific number of cycles,
or for continuous recycling.
Output of Data Acquired
with an AMMlA or
AMM2
Data can also be acquired through
an analog input channel, and then
sent back out through an AOM5
output channel. This technique is
useful for process control, sampling,
or output of waveforms which cannot be synthesized easily through
calculation. Foreground and background modes may both be used,
although the basic techniques and
applications wiU differ. Foreground
commands will provide operation in
real-time at the expense of speed,
while background commands wiII
be faster, but require input of aII
data before it can be output.
Before exploring these techniques,
note that the AOM5 provides 13 bits
of D/A resolution for four bipolar
ranges. The AMM2 uses a 16-bit A/
D converter, while the AMMlA uses
a 12-bit A/D converter, and both
Using the AOM5 Module
with
Figure 2. Read/Write with an AMMx andAOM5 Module
10
KDAC500
B
I.....rr;l
nr
AMM2 Module
1
’ Do foreground read and write in a loop
- INPUT
arra conversion,
Acquisition,
an processing
J
KDAC500
20 CALLKDINlT
.
I (BASIC and/or KDAC500 commands)
100 DIM VrN!(l)
110 DIM VOUT!(l)
120 I
200 CALL FGREAD’(“inchan”, “none”, vin!(>, “c.volts”, “nt”)
210 VOUT’!(O>=l.25*VIN!(O)+.3
220 CALL FGWRITE’(“outchan”, vout!O, “c.volts”, “nt”)
230 I$=INKEY$:IF I$=“” GOT0 200
:
: (BASIC and/or KDAC5OO commands)
.
900 CALLKDINIT
1OOOEND
Example 3. KDAC500/1 Foreground Read/Write
modules can be set for unipolar or
bipolar operation. Further, the
AMMlA actually provides 16-bit
results in which the four lowest
order bits are permanently wired
low. Therefore, the data formats of
signal. Fortunately, KDAC5OO’s
engineering unit conversion flags
(ETJF) make it possible to convert
data using ARGET and ARKIT
commands, without complex
conversions.
the AMM and AOM5 modules are
not l-to-l compatible. Passing an
array from an AMMx module
directly to the AOM5 as
unprocessed, binary data will not
give a reconstruction of the input
For a foreground read/write
using an AMMx and AOM5, first
execute a KDAC500 foreground read
(FGREAD) command to read an
analog input value. The reading
should be returned as a voltage by
setting the EUF in the FGREAD
command for voltage. Next, apply
any necessary conversions, offset, or
scaling to the voltage value. Finally,
write the value to the AOM5, also
using a voltage ETJF in the
FGWRITE command. This process
may be included in a loop as a form
of process control. The loop will run
at maximum speed in a compiler
version of KDAC500.
For background-oriented
operations, a BGREAD or ANINQ
command is first used to acquire
data with the AMM module and
place it in a KDAC500 array. The
next step depends on how large the
array is, and whether additional
processing of the array is necessary.
If the acquired data will fit a 64k
BASIC array, and if there is no need
for additional calculations on the
data, the ARGET command can be
used to convert the entire KDAC500
array to a BASIC array. Appropriate
voltage or current EUFs can be used
in the ARGET command. Next, an
ARPUT command converts the
BASIC array back to a KDAC500
array. This second KDAC500 array
must have been allocated previously
with an ARMAKE command. Once
converted, the new KDAC500 array
can be sent out through an AOM5
channel by setting up a BGWRITE
command and turning on interrupts.
If the data will not fit into a BASIC
array, or if additional calculations
are needed, a FOR-NEXT loop
containing ARGET and ARPUT
commands must be set up. The
ARGET command sequentially
reads each data value in the first
KDAC500 array and returns it as a
BASIC variable; engineering unit
flags can be used to express the
values as voltage, current, etc. The
Using the AOM5 Module
withKDAC500
loop may also include calculations to
offset or scale each value. Next, the
ARPUT command writes the value
to the second KDAC500 array. This
second array must have been BGWRITE command and turning on
allocated previously with an
’ Sample and output a waveform using background commands
10
20 ‘ AOM5 output range should match the AMM input range
30 CALL KDINIT
:
: (BASIC and/or KDAC500 commands)
:
100 CALL BGREAD’(“inarray%“, 5000., “inchan”, 1, “none”, 1, “nt”,
“readjob”)
110 CALL INTONq,“miP)
120 STAT%=-1
130 CALL BGSTATUS’f”readjob”, stat%)
140 IF STAT%<>0 GOT0 130
150 CALLINTOFF
200 4
300 DIM BASICARRAY!(5000)
310 CALL ARMAKE’(“outarray%“, 5000., “outchan”)
320 CALL ARGET’(“inarray%“, l., 5000., “inchan”, 1, basicarray!(),
“C.VOhs”)
330 CALL ARPUT’(“outarray%“, l., 5000., “outchan”, 1, basicarray!(),
“c.volts”)
400 ‘
500 CALL BGWRITE’(“outarray%“, “outchan”, 1, 1, “nt”, “writejob”)
510 CALL INTON’(l,“mil”)
520 STAT%=-1
530 CALL BGSTATUS’(“writejob”, stat%)
540 IF STAT%<>0 GOT0 530
550 CALLINTOFF
:
: (BASIC and/or KDAC500 commands)
ARMAKE command. When the
FOR-NEXT loop is complete, the
array can then be sent out through
an AOM5 channel by setting up a
interrupts.
900 CALL KDINIT
1OOOEND
Example 4. Ramp with KDAC500/1 Background Write
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: Keithley Instruments GmbH l Heiglhofstr. 5 l Mtinchen 70 l 089-71002-O l Telex: 52-12160 l Fax: 089-7100259
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: Keithley Instruments SARL l 3 All&e des Garays l B.P. 60 l 91124 Palaiseau/Z.L
NETHERLANDS: Keithley Instruments BV* Avelingen West 49 04202 MS Gorinchem*P.O. Box 559.4200 AN Gorinchem~01830-35333*Telex: 24 684eFax: 018303081
SWITZERLAND: Keithley Instruments SA l Kriesbachstr. 4 l 8600 Dttbendorf l 01-821-9444 l Telex: 828 472 l Fax: 0222-315366
AUSTRIG: Keithley Instruments GesmbH l RosenhiigeLstrasse 12 l A-1120 Vienna l (0222) 84 65 48 l Telex: 131677 l Fax: (0222) 84 35 97
ITALY:
Keithley Instruments SRL l Viale S. Giignano 4/A l 20146 Milan0 l 02-4120360 or 024156540 l Fax: 02-4121249
l
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