42
INM4500-2
Mar 2009
7.3 Analogue Input (AI) Modules
7.3.1 Modules: All variants
This test compares the output current with the input current over the normal range of operation.
Input Conditions
Connect the channel output to the channel input (+ to –, and – to +) as shown below.
Note
: Do not connect a voltmeter in circuit to measure V1 until requested in Step 4 below, because
current measurement A2 could be affected.
Output Measurements
Adjust RV1 to vary the current (A1) through the range 4 to 20mA.
The measured current imbalance (A2) over this range should not exceed ± 15
μ
A
Adjust RV1 for a 20mA reading on A1
The voltage V1, across the channel input, should be >16.5V.
7.4 Analogue Output (AO) Modules
7.4.1 Modules: All variants
This test compares the module’s output current with the drive current over the normal range of
operation.
Input Conditions
Connect the channel output to the channel input (+ to –, and – to +) as shown below.
The chosen (load) resistor can, in fact, be any value between 100 and 800
Ω.
Output Measurements
Adjust the current source to vary the current (A1) through the range 4 to 20mA.
The measured current imbalance (A2) over this range should not exceed ± 20
μ
A.
1.
1.
2.
3.
4.
1.
2.
1.
2.
+
+
A2
+
V1
i/p
o/p
RV1
10k
W
lin.
A1
+
+
A2
+
A1
o/p
i/p
current
source
+
470
W
load
Figure 7.5
AI test circuit
Figure 7.6
AO test circuit