micrologix 1200 analog output

[nmk34]

I need help achieving the following task:
ML1200 sending 4 to 20 mA thru analog output ch0 to a DC speed controller analog input(4 to 20 mA)

my thoughts:
1) at the HMI enter a desired dc motor speed and moved it to a PLC real register1. Range 0 to 100.
2) at the PLC, scale real register1 to be from 0 to 90 vdc and store in real register 2
3) at the PLC, scale real register 2 to be from raw data for analog output 0 to 32760 and moved to PLC analog output channel 0.

is there SCP instruction for ML1200?
are the steps above correct, redundant work?

 

[jaden]

I'm not sure why you are scaling the 0-90vdc on the motor. I would scale RPM desired to get the 4-20 ma signal to the motor controller. The motor controller probably has some adjustments to influence the actual motor speed.

 

[parky]

If you do not need zero & span capabilities then just take the 0-100 (in float format) & multiply it by 327.67 so 50.0 X 327.67 = 16383 i.e. 16ma
100.0 x 327.67 = 32767

 

[parky]

Forgot to add: convert the output back to integer or it may not compile