Resistors R1, R2, R3 And R4; Jumpers W3 And W4 - Brainboxes AD-1200 H User Manual

Reference
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Resistors R1, R2, R3 and R4.

There is provision for adding four optional resistors to the
ADMUX card.
R1 Precision 250 Ohms resistor.
Fit this when using the ADMUX card with 4-20m Amp
differential current inputs. Omit for thermocouple use.
R2 Nominally 10k Ohms
Fit with 10k nominal resistor to provide differential return
path to analog ground. This reference the Differential Input
signal to the ground on the AD1200 card. Omit when using
with the ISO122 isolation amplifier.
R2 Precision 250 Ohms
When using the relays for switching single ended current
input signals fit 250 Ohm precision resistor for 4-20m Amp
current to voltage conversion.
R3 Nominally 100M Ohms
This is for thermocouple break detection. When this resistor
is fitted, if the thermocouple breaks or if an open circuit
input is switched in the input line is pulled up to +2Volts.
See also VOPT jumpers and R14 below.
R4 Precision 250 Ohms
Fit this when using the ADMUX card with 4-20m Amp
differential current inputs. is the current to voltage shunt
Omit for thermocouple use.
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Jumpers W3 and W4.

Jumpers W3 and W4 should be left in place when using the
relays to switch differential inputs through to the AD1200 card.
Jumper W3 connects the system ground, SYS GND, to the
ANALOG ground. Single Ended inputs normally have a return
path via analog ground and this jumper connects the analog
ground to SYS GND.
Page 10
Analog Relay Mux Board
Diff Current Input Only!
Single Ended Current Inputs only!
Single Ended Current Inputs only!