Figure 1-4. Resistor Table, Se Inputs - Brainboxes AD-945 Supplementary Manual

Analog Terminal Board
turning the 4-20mA inputs into voltages. Set the A/D card for 8
channels differential input, Unipolar 0-5 Volt range. Install the
current shunt resistors. These should be high precision 250 Ohm
resistors, 0.01% or better. These give an output voltage of
250mV per mA. Thus 4mA gives 1 Volt input, 20mA gives 5
Volts input, 0 volts input is open circuit.
The current shunt resistors for channels 0 to 7 are R13, R9, R5,
R1, R16, R12, R8 and R4 respectively. See Figure 1-3. Only
resistors for the number of channels actually being used in this
mode need be fitted.
In exceptional circumstances 16 current inputs may be used,
when the AD1200 card is set to 16 SE or 16 Pseudo DI inputs.
In this case the resistors R14, R10, R6, R2, R15, R11, R7 and
R3 marked out as DI 10k return resistors and R18, R20 and
R50-55 should be fitted with the 250Ohm 0.01% tolerance
current shunts as shown in Figure 1-4.
________________________________ _

Figure 1-4. Resistor Table, SE Inputs.

Resistors 16SE and 16 Pseudo DI Settings
Function
4-20mA
Current
Inputs
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
R R R R R R R R R R R R R R R R 250R
51 50 25 18 55 54 53 52 14 10 6 2 15 11 7 3 %tol
Reference
0.01
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