converting slc 150 internal timer to slc 500

[J Golob]

____internal______backup _____________________one scan
____pulser________function_____________________pulse at
____50ms clock____797__________________________50ms
______872__________796________________________797
-------] [------------] [-----------------------------( )--


____872_______________________________________796
-----]/[----------------------------------------------( )--


This logic is used about 3 different times with different internal pulse timers in the program and I'm curious if anyone has a good idea on how to convert this to rslogix 500. I would consider myself entry level with rslogix 500 but I pick up stuff fast, so any input would be greatly appreciated.

 

[OkiePC]

Looks like they're creating a oneshot pulse every 50ms. You could do that with a timer in RSLogix500:

    T4:0                   
----]/[---------------TON
      DN             T4:0
                     Timebase: 0.01
                     Preset: 5

     T4:0             B3/796
----] [--------------(  )
      DN

The above would be similar, but would likely end up losing a few milliseconds every now and then due to scan time.

How critical is it that it be exactly 50ms?

If it is critical, you could set up an STI routine to run, for example, every 25ms and toggle a bit, then look for a rising edge in the regular logic...this introduces other issues like the fact that an STI routine could run at any point during the main logic scan.

 

[J Golob]

Sorry about the edit above. I only have a hard copy of this program and we are in the process of updating this equipment. From what I can gather from the information I have and watching the equipment I don't think 50ms exactly is critical. I'll try this and see what happens. Thanks