Derivatives on GE Series 90-30 PLC


Thread Starter


I was just wondering if anyone could help me with any code that finds the first derivative of velocity in the series 90-30 GE PLC using
logicmaster90 software. Also if anyone had some code or advice which can do a low pass filter that would be great. I am new to PLC's and i
am stuck. Thankyou


Steve Bailey

First rung:

Use the 100 mS internal bit %S0004 to fire a one-shot coil.

Next rung:

Use a contact from the one-shot to enable a subtract instruction where you subtract the previous value of the velocity from the current
value. Then divide the result by 100 milliseconds. The result of the division is acceleration (Delta V divided by Delta t).

Next rung:

Move the current value for velocity into the data register for the previous value.

If you need a different time resolution, you can create a self-resetting timer.