start and stop output signal to start/stop a motor

My controllogix PLC uses a start output and a stop output to start and stop a motor respectively. The start and stop output is a 5 sec pulse.

The attached picture is my way of implementing the logic. When bit[0],1 or 2 turns on, it triggers the OSR instruction. The output bit of the OSR instruction latches on the TON timer to provides a 5 sec pulse output. When rung 0 is false (bits 0,1,2 are off), the OSF instruction latches on TM[1] to produce a stop signal. Tm[1].tt is tied to stop signal output and tm[0].tt is tied to the start signal output.

Is there a better way to implement the logic described above? Are any potential problems with the logic?

Hi,

There are several ways to achieve what you describe. Your logic should work. My only comment is that, typically, we use a maintained output for the STOP signal which then pulses OFF to stop the motor. Then at least you have added an element of 'fail safe' to your application where the motor will stop in the event of a power loss or failed output.

Hope this helps.

Regards,

Rob