Text preview for : 501_901_01C.pdf part of Keithley 501 901 01C Keithley 501 501_901_01C.pdf
Back to : 501_901_01C.pdf | Home
AIMS
Strain Gage and DC Amplifier Module
This documentation describes the features, installation, and operation of the AIM8
Strain Gage/DC Amplifier Module for the Series 500 and System 570. This manual also
contains specific progra mming information which is essential to understanding and us-
ing the AIM8 module.
This manual is not a general-purpose source on strain gages or DC measurement
techniques. The user must select strain gage transducers and bridge configurations ac-
cording to the application. For specific applications information on strain gages, consult
the literature produced by strain gage manufacturers.
The AIM8 is a highly versatile module used to measure strain-related parameters. It is
compatible with a wide variety of resistive and semiconductor strain gage transducers.
The AIM8 includes several advanced features which contribute to its performance, ac-
curacy, and overall flexibility.
Four channels: The AIM8 has four channels. Each can support a full, half, or
quarter strain gage bridge. The AIM8 supports the use of quarter bridges with or
without lead compensation.
High-gain, low-noise amplifier: The AIM8 offers software-programmable local gains
of 1, lo, 100, or 1000. Local gain can be combined with global gain for total gain of
up to lO,OOO. Maximum noise is 2V peak-to-peak to lOI&, and 4pV p-p from 1OHz
to lkH.2.
High sensitivity: The AIM8 provides usable measurement sensitivity in the
microvolt region.
Extensive transducer compatibility: The AIM8 accepts resistive and semiconductor
strain gages with values from 1203 to several thousand ohms.
On-board bridge completion facilities: The AIM8 includes spring-loaded pin sockets
for quick installation of jumpers and bridge completion resistors directly on the
module.
Adjustable excitation: The AIM8 provides regulated, independently-adjustable excita-
tion of OWOV at up to lOOmA for each of its four channels.
Internal or external excitation: Power for the on-board excitation sources is derived
from the data acquisition system +l5V supply. The AIM8 contains on-board ter-
minaIs for connection of an external excitation power supply if necessary.
Document Number: 501-901-01Rev. C AIM84
Excitation voltage readable via software: Internal AIM8 channels 4, 5, 6, and 7 read
the excitation voltage of channels 0, 1, 2, and 3, respectively.
Quick-disconnect terminals: The AIM8 includes quick-disconnect' terminal blocks for
easy connection to strain gages and an external excitation power supply.
Selectable low-pass filter: The AIM8 offers lOHz, lkHz, or 3kHz (no filter) band-
widths, selectable through IONAME parameters.
Adjustable offset: An offset of up to flOOmV or rtlV is available to null bridge im-
balance, or for "zero suppression" during standard DC measurements.
Compatible with Series 500 or System 570: The System 570 accepts one AIMS. The
Series 500 can accept up to nine AIM8 modules. (External excitation power may be
required.)
These features are important in measuring strain gages, but are also useful in many
other applications which measure millivolt and microvolt signals. In addition, the
bridge completion sockets permit a Wheatstone bridge to be configured for sensitive,
bridge-type voltage measurements. Figure 1 shows the important features of the AIM8
module.
AIM8-2
IL
" ul
w a
Figure 1. AIM8 Module
Requirements for Using the AIM8
The AIM8 is hardware-compatible with Keithlefs Series 500 and System 570 products.
When used in the Series 500, the AIM8 requires a master analog input module AMMl
or AIM1 in slot 1. The AIM1 requires either an ADMl or ADM2 A/D module in slot 2.
The System 570 already contains the master analog input and A/D functions, and is
ready to accept one AlM8.
AIM8 progr amming is done with Soft500 Version 4.0 or later, or Quick500. Soft500 runs
under IBM PC Advanced BASIC (BASICA), Compaq BASICA, or Microsoft GWBASIC.
IBM DOS version 3.1 or later is recommended.
AIM83
Compaq computers must run Soft500 under Compaq DOS 3.0 or later, with the mat-
ching BASICA version. Earlier versions of Compaq DOS and BASICA are not compati-
ble with Soft500 V4.0.
Soft500 Version 4.0 or later also runs on most 100% IBM-compatible computers which
use MS-DOS, Version 3.0 or later, and WBASIC. Regardless of the brand or rev level
of the DOS, use the GW-BASIC version which accompanies or is recommended for the
DOS version. Mixing DOS and BASIC versions may cause problems.
The AIM8 module can also be programmed directly using BASICAs PEEK and POKE
functions, or the corresponding memory read and write functions of other programm-
ing languages. This permits the AIM8 to be programmed outside the Soft500
environment.
installation
InstaIl the AIM8 in slots 2-10 on the Series 500 (slots 3-10 if the AIM1 is used). For max-
imum immunity to noise, install the AlM8 and any other analog input modules in the
lowest-numbered available slots. The System 570 can accept one AIM8 module in its op-
tion slot. For either system, update the configuration table to show the location of the
AIM8 by running CONFIGEXE.
User-Configured Features - Strain Gage Function
Before you install the AIM8 in a Series 500 or System 570, you must configure the
AIM8. InstaIl or remove jumpers and bridge completion circuitry according to the
operating parameters and type of bridge connected to the module. Each of the follow-
ing paragraphs discusses a feature you must configure before you use the AIM8
module.
Connecting a Bridge to the AIM8
The AIM8 card has one quick-disconnect terminal block per channel. Each block has
screw terminals for (+) and (-) signal input, analog ground and shield, and excitation
output Vss (see Figure 2).
Make connections to the AIM8 by first loosening the terminal screws several turns.
Strip 114inch of insulation from a wire lead, insert the lead in the receptacle beneath
the screw, and tighten the screw.
To help with connection of leads, you can remove the terminal blocks. Pull a block off
the board in a perpendicular direction with a firm, even pressure. Do not pry the ter-
minal blocks off with a screwdriver or sharp tools or you may damage the circuit board.
After you connect the wires to the terminal block, reinstall the block on the AIM8.
Completing the On-Board Bridge Chuitry
The AIM8 module contains four sets of pin socket terminals for completing bridge cir-
cuits on the AIM8. These pm sockets are organized into groups O-3, which correspond
to the AlM8's input channels. within each group, pairs of pm sockets are labeled Rl,
R2, R3, R4, WY-l, Wl-2, and W2 (see Figure 2).
e- h GND
- zzmr2 - -
J- 0+
e- L------- RS t--
e- ; ---A
-W>-L-@
e- J-- -Ri----P- vsso
L- ------
e- ; ---A
w1-2-L -@
A-- -52--+- O-
L- ------
* JUMPER SET AND DESIGNATIONS
REPEATED FOR EACH CHANNEL.
A GND
.L I I
Figure 2. AIM8 On-Board Bridge Completion Circuitry
Each pin socket accepts a single, solid-wire jumper or resistor lead. Maximum accep-
table lead diameter is 0.020 inch. The spacing between jumper sockets is 0.5 inches,
while the spacing between resistor sockets is 0.8 inches.
Bridge completion resistors must have a low temperature coefficient. Keithley ships 12
low-X l2O-ohm resistors and 12 low-K 350-ohm resistors with the AIMS. These
resistors have temperature coefficients on the order of l.Oppm/"C. Resistors which do
not meet this specification may compromise the accuracy of the AIM8. Keithley also
AlM8-5
ships a supply of jumpers with the AIM8. These resemble resistors, and have a blue
body with a single black band indicating O&
Cut the jumper or resistor to length, bend the ends at right angles, and plug the ends
into the pm sockets (see Figure 2). Each pin socket is spring-loaded, and will grip the
wire lead firmIy until the lead is removed.
Table 1 summarizes the bridge completion information for the four common bridge
configurations.
Table 1. Jumpers and Resistors for Bridge Completion
CONFIGURATION Rl R2 R3 R4 Wl-1 Wl-2 W2
Full Bridge 0000x 1 0
Half Bridge 1100x x 0
Quarter Bridge w/o 1 1 1 0 1 X 0
lead compensation
(2-wire)
Quarter Bridge with 1 1 1 0 0 0 1
lead compensation
(3-wire)
Voltage Measurement 0 0 0 0 X 1 0
(no bridge)
1 = installed
0 = not installed EXCITAT
X = Don't Care
SIGNAL(+)
-SIGNAL(-)
EXCITATION AND(-) 1
ANALOG GROUND
Full Bridge
The full bridge uses four active strain gage elements, all of which are located external to
the AlM8. The fuE bridge circuit uses no on-board completion elements, but it does re-
quire that a jumper be installed on the AIM8.
For the full bridge circuit, install jumper Wl-2. Jumper W2 should not be installed. Wl-1
makes no difference. Do not install any bridge completion resistors Rl-R4. See Figure 3.
AIM8-6
@+ WI-2 +-@ INSTALL JUMPER Wl-2.
~ Ml-1 IN OR OUT. NO W2.
@
I I
INSTRUMENTATION I
AMP
CIRCUITRY
Figure 3. Full Bridge Circuit and Jumpers
Half Bridge
The half bridge uses two active strain gage elements and two passive resistors to com-
plete the bridge. The strain gage elements are located external to the AlM8, while the
completion resistors are installed on the AIM8.
To complete the half bridge on the AIM8, install bridge completion resistors Rl and R2.
Do not install jumper W2. Jumpers Wl-1 and Wl-2 make no difference. See Figure 4.
AIM81
INSTALL BRIDGE COMPLETION
RESISTORS Rl AND R2. Wl-1
AND Wl-2 IN OR OUT. NO W2.
----.
----------------_-____
I
---------------_______ I
Figure 4. Half Bridge Circuit and Jumpers
Quarter Bridge Without Lead Compensation
The quarter bridge without lead compensation uses one active strain gage element plus
three resistors located on the AIM8 to complete the bridge. Two leads connect the ac-
tive gage to the AlM8.
Use the 2-wire configuration only for short wire runs between the data acquisition
system and strain gage. Long runs can introduce resistive and thermal effects which
degrade measurement accuracy.
For the quarter bridge non-compensated configuration, install bridge completion
resistors Rl, R2, and R3. Install jumper WI-l. Jumper W2 should not be installed.
Jumper Wl-2 makes no difference. See Figure 5.
A&W8
INSTALL JUMPER WI-1 AND
__________-___---_----------
1
I
I
I
I
_-_____--_------------------
Figure 5. Quarter Bridge/2-Wire Circuit and Jumpers
Quarter Bridge With Lead Compensation
The quarter bridge with lead compensation uses one active strain gage element plus
three resistors located on the AIM8 to complete the bridge. Three leads connect the
strain gage to the AIM8. The three-wire configuration minimizes the errors caused by
thermal effects and resistance of the connecting wires.
For the quarter bridge lead-compensated configuration, install bridge completion
resistors Rl, R2, and R3. Install jumper W2. Do not install jumper N-1 and Wl-2. See
Figure 6.
AIM&9
0 @ INSTALL JUMPER W2 AND
e-j W2 j----Q3 BRIDGE COMPLETION
RESISTORS Rl, R2 AND R3.
Rl f---+3 NO WI-1 OR Wl-2.
--------------a-----------
I
I
l I
I rs\ I
`\-R3 [ w I I1
V i
I
-----_-----__------------a
Figure 6. Quarter Bridge/3-Wire Circuit and Jumpers
Selecting Excitation Power and Adjusting Excitation Voltage
The AIM8 contains an independent excitation source for each of its channels. Each
source is a voltage regulator circuit with current limiter. Potentiometers labeled VssO-Vss3
vary the excitation voltage of channels O-3. Each excitation source can supply 0 to 10
volts, with maximum current limited to lOOmA.
The AIM8 is normally configured so that the excitation sources are powered by the data
acquisition system +15V supply. Alternately, an external excitation power supply can be
connected to the AIM8 to drive the excitation sources. In this case, potentiometers
VssO-Vss3 adjust the excitation level, and current output remains limited to lOOmA.
still
The choice of internal vs external power for excitation depends on four factors:
1. The number and resistances of the bridges connected to the AM8.
2. The excitation voltage level set for each strain gage channel.
3. Whether the data acquisition system is a System 570 or Series 500.
4. The types and numbers of any other modules installed in the data acquisition
system.
AIM&IO
Unless you will be connecting an external supply, move jumper W5 to the INT l5V
position. To select an sttemal excitation supply, move jumper W5 to the EXT l5V posi-
tion (see Figure 7).
The AIM8 contains a quick-disconnect terminal block for connecting an external excita-
tion power supply. This block has two screw terminals for +V and two for analog
ground (A GND). Th e extra terminals for +V and A GND enable several AIM8's to be
daisy-chained off one external excitation supply.
The voltage of an external supply should be at least two to four volts higher than the
maximum excitation voltage desired from the AlM8. On the other hand, avoid running
the AIM8 excitation at just a few volts with high voltages (20V or more) connected for
external power. Large voltage margins require that the AIM8's regulation circuitry
dissipate the excess power. This may generate excessive heat and lead to component
failure on the AIM8.
To connect an external supply, first loosen an external excitation +15V screw and an A
GND screw on the excitation terminal block (see Fiie 7). Connect the external power
supply to the terminal screws. Observe the polarity markings on the AIM8 and connect
the external supply correctly or you may damage the AIM8.
To connect two or more AIM8 modules to the same external excitation power supply,
you must link the external power connectors of all AIM8's. Connect a wire from one
+l5V terminal screw on the second AIM8 to the unused +l5V terminal screw on the
first AIM8. Connect a second wire from one A GND screw on the second AIM8 to the
unused A GND screw on the first AIM8. Repeat these connections from a third AIM8
to the second AIM& and so on. Be sure to move the W5 jumpers on all AlM8 modules
to the external power position.
Even though the AIM8 can supply up to lOV excitation, it is common for bridges to be
driven at one to a few volts. A strain gage draws less current at lower excitation
voltages, which minimizes heating effects within the strain gage. A second benefit is
that, at lower voltages, strain gages draw less total power from the +l5V supply. This
maximizes the number of strain gage bridges that can be driven without resorting to an
external power supply.
Table 2 gives the current requirements for common bridge values for a single channel
driven at 0.5, 1, 2.5, 5, 7.5, and 10 volts.
Table 2. Per Channel Current Requirement (mA)
(rounded up to nearest O.lmA)
Bridge Resistance
Excitation Voltage 12012 3503
0.5v 4.2 1.5
1v 8.4 2.9
2.5v 21 7.2
5v 41.7 14.3
7.5v 62.5 21.5
10 v 83.4 28.6
AIMS-11
EXCITATION ADJUST
POTENTIOMETERS
A GND
> c-1
INTERNAL 0 +15v
Ll >
EXTERNALLOJ
Figure 7. AIM8 Excitation Terminals, Jumpers and Adjustment
External Excitation With the System 570
The System 570 can supply approximately lOOmA at +l5V to its option slot. The AIM8
itself requires 75mA, which leaves 25mA for excitation. Therefore, a System 570 can
drive a single l2OQ bridge or three to four 35OQbridges at 2.5V For other voltages,
bridge resistances, or numbers of bridges, calculate the current requirement using
Ohm's law. If the total required current (including 75mA for the AIM8) exceeds lOOmA,
an external excitation supply will be necessary.
External Excitation with the Series 500
The Series 500 can supply a total of 5OOmA at +l5V. Approximately 250mA is available
to an AIM8 module in a lightly- or normally-loaded Series 500. This leaves 175111~4
for
excitation. However, analog output, power control, and digital output modules place
heavier burdens on the Series 500's +l5V supply.
If you are in doubt about the total current consumption at l5V, consult the Series 500
hardware documentation for the power requirements of each of the installed modules.
Calculate the total current draw at +l5V including 75mA for the AlM8, plus what is
needed for bridge excitation. If this total is more than 5OOmA, connect an external ex-
citation supply to the AIM8 module(s).
AIM-12
Setting the Excitation Voltage
Regardless of whether you select internal or external excitation power, adjust excitation
potentiometers VssO-Vss3 the desired voltage at AIM8 terminals VssO-Vss3
for (see Figure
7).
The AM8 excitation voltages can be read via software. Channels 4 to 7 are hard-wired
within the module to read the excitation voltage set for channels O-3, respectively. A
ninth channel, channel 8, is an internal channel connected to ground, and should
always read OV. These channels are only for reading excitation, and are not accessible
for monitoring external signals with the AlM8.
The following Soft500 program reads the excitation voltage set for channel 0 of an AM8
installed in slot 8. The IONAME parameters, in order, are as follows: ION$ (signal
name) = `W, AlM8 slot = 8, signal channel = 4 (channel 0+4), AID accuracy = 12
(bits).
10 va=O
20 cls
30 call ioname'("EXV':8,4,l2)
40 call anrea&("EXV'~va,O)
50 locate 1,l:print va
60 goto 40
This program continuously reads channel 4 to monitor the excitation voltage set for
channel 0. Likewise, channel 5 reads channel 1 excitation, channel 6 reads channel 2 ex-
citation, etc.
Soft500 reads the excitation voltage in the course of using engineering unit flags 70 and
7l. Your application may require precise setting of the excitation; however this is not re-
quired for the benefit of Soft500.
Selecting a Filter
The AlM8 contains low-pass filter circuitry to reduce the effect of noise on the AIM8 in-
put. Out-of-band noise shows up as spurious counts from the AID converter. Software
selects cutoff frequencies of lOHz, lkHz, or 3kHz. The 3kHz filter setting is the
equivalent of disabling the filter. Select the lowest filter cutoff frequency which still
passes the desired signal. Unless you require a particular filter, select 1OHz.
When enabled, the filter function affects all channels. However, different filter frequen-
cies can be selected for each channel with the IONAME FIlT% parameter. This
parameter is part of the IONAME command structure. Consult the Soft500 IONAME
documentation for information on specifying parameters. Note that beginning with
Soft500 Version 4.0, IONAME's can be specified as part of the hardware configuration
process.
AIM&13
Configuring the Offset Feature
The AIM8 dual-range offset circuit can apply offsets of up to flOOmV or *lV full-scale
against the input signal. The offset feature makes it possible to trim a bridge which is
out of balance under no-Ioad conditions. For standard voltage measurements, the offset
feature facilitates measurement of minute signal variations which ride on a steady DC
component of greater amplitude.
Potentiometers OSO-OS3 set the offset level for channels O-3, respectively (see Figure 8).
The offset circuitry multiplexes each offset level to the AIM's instrumentation amplifier.
This assures that each offset level is applied to the intended input channel.
Figure 9 shows a simplified equivalent of the offset circuit. Note that the offset circuitry
sums the (+) signal input with the offset voltage before it is amplified by the AIM& in-
strumentation amplifier.
OFFSET ADJUSTMENT
POTENTIOMETERS
"====t I OFFSET*
"I 1 eL
ENABLE
--- RANGE
Vnc SELECT
,
*lVos POSITION GIVES flOOmV OFFSET RANGE.
10Vos POSITION GIVESflV OFFSET RANGE.
Figure 8. AIM8 Offset Adjustment Potentiometers and Jumpers
AIMS-14
+ IOV
P
-lov f \
IOOmV
OFFSET
ADJUST
(+I
INPUT
>-
P R OFFSET
RANGE
N Y
10R l
Figure 9. AIM8 Offset Simplified Circuit
Software selects or deselects the offset function. However, you must first enable the off-
set hardware and select the range by positioning jumpers on the AIM8 (see Figure 8).
Jumper W3 selects between Voltage Offset Enabled (vos-3') or Voltage Offset Disabled
(vos-N). Jumper W4 selects either the 1V offset or lOOmV offset levels. The positions of
jumper W4 are labeled "VOS 10" and "VOS I" The "10" position sets a final maximum
offset of *lV, and the `3" position sets a final maximum offset of ItlOOmV.
Normally, you should select the lowest offset range suitable for the application. This
will assure the lowest temperature coefficient, which improves the overall stability of
the offset adjustment. Thus, if the maximum offset to be applied is 1OOmV less,
or
select the ltlOOmV offset range.
Unless you have a specific application in mind, enable the offset feature by moving
jumper W3 to the "VosY" position and jumper W4 to the "VOSlO" position. Later, you
can move W4 to the TO%" position if the lower offset range will be adequate.
Setting Offset for Strain Gage Bridges
For nulling bridge imbalance, first connect the strain gage bridge to the AIM& Con-
figure the AIM8 according to the instructions in the previous sections for full, half, and
quarter bridges. Set up the strain gage experiment as it will be used during data ac-
quisition, with no load applied.
Adjust the offset level for channels O-3 with potentiometers VosO-Vos3,
respectively. The
following Soft500 example program assumes a strain gage bridge connected to channel
0 of an AIM8 in slot 8. IONAME parameters, in order, are as follows: ION$ (signal
name) = "OFFSET", AIM8 slot = 8, Signal channel = 0, A/D accuracy = 12 (bit), GA%
(global gain) = 1, LGA% (AIM8 local gain) = 10, FII.T% = 0 for no filter, and OFF!E%
= 1 for offset enabled.
lOva=O
20 call ioname'("OFFSET",8,O,l2,l,lO,O,l)
30 call anread'("OFFSET"va,O)
40 locate 1,l:print va
50 got0 30
Adjust the offset level for channel 0 with potentiometer VosOuntil the voltage reading is
0. Genera.Uy, a total gain of 10 to 1000 will give sufficient sensitivity for offset adjust-
ment. For more precise zeroing of offset, increase the gain by increasing the value
entered for the GA% parameter (1, 2, 5, 10) or the LGA% parameter (1,. 10, 100, and
lOOO),and readjust for OV.The optimum adjustment will often produce a small non-
zero reading with flashing polarity sign, rather than a reading of 0.
Note: After you have experimented with jumper W4 in the "VOSlO" position, move W4
to the "VOS l" position and rerun the program. If you can zero the bridge with W4 at
VOS 1; use that position.
Voltage Measurement with the AIM8
The AIM8 can be used for general-purpose voltage measurements. Its instrumentation
amplifier features low noise, high gain, and differential input. The AIM8 full-scale
voltage input ranges are &lOmV, klOOmV, *lV, and ltlOV full-scale. These ranges corres-
pond to local gain (LGA%) parameters of 1000, 100, 10, and 1.
The AIM8's local gains (LGA%) can be programmed in combination with the global
gain (GA%) of the AIM1 or AMMl. This gives equivalent gains of 1, 2, 5, 10, 20, 50,
lO0, 200, 500, l.000, 2000, 5000, or lO,OOO.
The ADMl and ADM2 A/D modules offer l2-
and 14bit resolution, respectively, with input ranges of &UJV f5V, f2.5V, O-1OV and
O-5V These give the AIM8 a versatile range of bit resolution and full-scale sensitivities.
With XX-bit A/D conversion, resolution of the &lOrriV range (GA% = 1 and LGA% =
1000) is 2OmVkO96,or 4.88 microvoltslstep. Progr amming GA% = 10 gives a *ZmV full-
scale input and a theoretical resolution of 488nV. Fourteen bit A/D gives l22riV resolu-
tion. However, system and environmental noise limit the usable low-level threshold to a
few microvolts, regardless of A/D range.
AIM8-16
For voltage measurement, connect the input signal directly to the (+) and (-) input ter-
minals of an AIM8 channel. InstalI jumper WI-2 to complete the path from the (-) in-
put terminal to the amplifier. Do not install jumper W2; jumper Wl-1 makes no dif-
ference (see the full-bridge diagram, Figure 3).
For single-ended operation, connect the (-) channel input to the analog common (A
GND) terminal. Apply the signal to the AIM8 (+) and (-) input terminals. For differen-
tial operation, connect the signal high to the AIM8's (+) input, and connect signal low
to the AlM8's (-) input.
To return readings which are expressed in voltage units, use an engineering unit flag of
0 for volts, 1 for millivolts, or 2 for microvolts with ARGETUAL, ANREAD, or AR-
WRlTE commands.
Of the AM8's various strain-related features, the Local Gain, Filter, and Offset are also
useful for standard voltage measurements. Program the Local Gain and Filter functions
the same as for strain gage measurements. Refer to the following instructions for using
the offset function during voltage measurements.
Using Offset for Voltage Measurements (Zero Suppression)
For straight voltage input, the offset feature facilitates measurement of minute signal
variations which ride on a steady DC component of greater amplitude. The offset
voltage can be set to cancel the larger voltage componetit, leaving only the signal of in-
terest for amplification. This technique is often called "zero suppression".
A typical example would be a &3OmVp-p fluctuation which is impressed on a steady
0.5V DC component. The AIM8 can apply a -0.5V offset, leaving only the 30mV signal.
Greater gain can then be applied to the 30mV signal without saturating the AIM8 in-
strumentation amplifier.
The easiest method for setting such an offset is to use SoftSOO's
graphing capability.
Visually check the DC component of the signal, and then adjust the offset control until
the signal fluctuates symmetrically about OV.
The following program uses the analog input command ANTN and the real-time
graphing command HGRAPHRT to acquire and plot voltage readings. The data acquisi-
tion and graphing run continuously. You can stop the program at any time by pressing
the escape ("Esc") key.
The program assumes the following conditions and parameters:
The AIM8 module is in slot 8, with the signal connected to channel 0. X&bit A/D
accuracy is specified, with the gain (GA%) set to 1 and the local gain (LGA%) set
to 20. FII.T.46is set to 1 to select the 1OHz filter. Initially, OFFE% is set to 0 to
disable the offset feature. Later, you will be instructed to enter a 1 for OFFE% to
enable the offset.
AIM847
10 SCREEN 2:CLS:KEY OFF
20 CALL IONAME'("offset"~,O,l2,l,lO,l,O)
30 LOCATE 25,31:PRINT `TRESS Esc TO EXIT";
40 LOCATE l3,l:PRINT "0";
50 CALL ANIN'("arg%",l.~offset'~l,-l/grph")
60 CALL INTON'(l,"miI")
70 CALL HGRAl?HRT'("grph"~"l"j'scrolI':"-1, "r;W,-l,l,"grid")
80 CLS
90 CALL INTOFF
As a starting point, apply the signal to the (+) and (-) inputs of channel 0. Run the
program and check the overaIl level of the signal. If necessary, increase the GA% and
LGA% parameters to get a good picture of the input.
NOTE: There are only a few parameters to be changed if you need to experiment with
different offsets and voltage inputs.
In line 40:
GA% (1, 2, 5, 10)
LGA% (1, 10, l.00, 1000)
OFFE% (0, 1)
I
CALL IONAMX'("offset'~8,O,l2,l,lO,l,O)
The GA% parameter controls the gain of the master analog input module. The LGA%
parameter controls the gain of the of the AIM8 instrumentation amplifier. As set, these
parameters give an overall gain of lo, and the system will accommodate a signal-plus-
offset range of flV. Alter one or both gains to match AIM8 input range to other signal
or offset levels.
In line 90:
The "MINY'L!