irondesk40
Member
Have some machines that i used a micrologix 1400 plc and using thermocouple inputs and outputs to control solid state relays to maintain the desired temperature of some press molds on some machines. With this setup the temperature can be maintained with 1 degree of accuracy from 0-420F.
Now looking at swapping out the micrologix with a compact logic 1769-L24er and working at the bench to duplicat the program.
Running into a issue with the temperature control. IN the micrologix i use the control variable output to determine the preset times for timers used to turn on the outputs to solid state relays. If the desired temperature requested is higher than the actual output then the control variable of the PID is a larger number. As the desired temperature gets closer to the actual temperature the value of the control variable gets smaller which causes shorter output cycles to the solid state relays.
Trying to simulate this with the compact logix and the control variable is always either 0 or 100%, it never varies from 0-100%.
Confused as to what i am doing wrong. Could someone that has a lot more experience with the compact logix take a look and see what i am doing wrong. I will attempt to attach some screen shots. Due to the 300k size limit had to break them up into mulitple screen shots.
Thanks
Now looking at swapping out the micrologix with a compact logic 1769-L24er and working at the bench to duplicat the program.
Running into a issue with the temperature control. IN the micrologix i use the control variable output to determine the preset times for timers used to turn on the outputs to solid state relays. If the desired temperature requested is higher than the actual output then the control variable of the PID is a larger number. As the desired temperature gets closer to the actual temperature the value of the control variable gets smaller which causes shorter output cycles to the solid state relays.
Trying to simulate this with the compact logix and the control variable is always either 0 or 100%, it never varies from 0-100%.
Confused as to what i am doing wrong. Could someone that has a lot more experience with the compact logix take a look and see what i am doing wrong. I will attempt to attach some screen shots. Due to the 300k size limit had to break them up into mulitple screen shots.
Thanks