SLC 5/05 SQO Instruction

[Operaghost]

I think they need a better way to trigger the 3 second timer. I was running this yesterday and the .POS did appear to jump from 2-4 and 4-6. That's probably due to it being emulated and in a VM that was probably running low on RAM. Running it today, I can see the steps more clearly.

OG

 

[drbitboy]

If the SQO output bits can be indirectly addressed, then why not the TON .PREset as well? The Start/Stop Circuit could be jazzed up to handle the additional logic, and the .PREsets in Data File N254 for steps 2, 4 and 6 would be 900s, 180s, and 300s (15min, 3min, 5min), respectively, but this does pretty much what OP's LAD 6 does.

 

[OkiePC]

If the SQO output bits can be indirectly addressed, then why not the TON .PREset as well? The Start/Stop Circuit could be jazzed up to handle the additional logic, and the .PREsets in Data File N254 for steps 2, 4 and 6 would be 900s, 180s, and 300s (15min, 3min, 5min), respectively, but this does pretty much what OP's LAD 6 does.

View attachment 61591

Back in my tire assembly days, we used a lot of sequencers and often we would use the position value and an array of elements with indirect addressing to load timers for things like maximum or minimum time in a step. Most of ours also used SQI. Eventually I figured out that I didn't like some of the restrictions of the SQI/SQO instructions so I started just using MVM with indirect addressing with external logic to manipulate the step number.

I think I uploaded a generic example to MrPLC many years ago.

Sequencers can be very powerful and were all but necessary to fit the control logic for a complex assembly machine into a PLC with only 4K ram back in the late 70s. But if you don't keep them "clean" and well documented, they can be a bear for the guy who has to troubleshoot them later.

 

[I_Automation]

If the SQO output bits can be indirectly addressed, then why not the TON .PREset as well? The Start/Stop Circuit could be jazzed up to handle the additional logic, and the .PREsets in Data File N254 for steps 2, 4 and 6 would be 900s, 180s, and 300s (15min, 3min, 5min), respectively, but this does pretty much what OP's LAD 6 does.

View attachment 61591

most Sequencers I work on include a timer or counter Preset for that specific step. All written to a single Cycle timer or counter.