Ge ic694alg223

Hi all

Is it better to set the GE IC694ALG223 analog card to 0-20mA and then scale it in a function block.
Even though the device attached is 4-20mA.

Selecting 4 - 20 mA or enhanced 4 - 20 mA gives you better resolution.

Set for 4 - 20 mA, a signal of 4 mA results in a value of zero and 20 mA results in a value of 32000 in the %AI address.
Set for enhanced 4 - 20 mA (4,20mA+), a signal of zero mA results in a value of -8000, a signal of 4 mA results in a value of zero and a signal of 20 mA results in a value of 32000 in the %AI address.
Set for 0 -20 mA, a signal of zero results in a value of zero and a signal of 20 mA results in a value of 32000 in the %AI address.

4 - 20 mA and enhanced 4 - 20 mA both give you a data value range of 32000 counts corresponding to a span of 16 mA.
0 - 20 mA gives you a data value range of 32000 counts corresponding to a span of 20 mA.
Note that in all cases, the A/D conversion is twelve bits (one part in 4096), so that range of 32000 counts occurs in steps of eight. The values you will see in the %AI address will be 8, 16, 24, 32, ... 31984, 31992, 32000. You won't see any values between those steps.