Why does this NOT re-cycle after delay

TheWaterboy · Sep 1, 2021

In the code below I have what should be, in its current condition, a simple cycling up counter with a delay before recycling.
But as it is shown it counts up only one time and then stalls. I must be missing something really obvious here.
Please tell me what it is.

drbitboy · Sep 1, 2021

reverse the order of the bottom two rungs.

always assume the PLC is doing exactly what you told it to do; what you want it to do, or expect it to do, or think it should do, is irrelevant. Therefore, we note the irony of your location as "State of Denial"

; we've all been there; many times

It is actually counting up more than once; it is counting up to 3 continuously, once per scan, as plvlce notes.

cardosocea · Sep 1, 2021

Disregard comment.

plvlce · Sep 1, 2021

Assuming that the EnableStation bits are 0...

Once Station reaches 3 (ie >TotalStations), then each scan cycle your first rung shown MOVes 1 into Station (where your arrow is pointing). Since Station is now 1 and [Blur].EnableStation is 0, the second rung adds 1 to Station. Since Station is now 2 and [Blur].EnableStation is 0, the third rung adds 1 to Station. When the logic reaches the first rung in the following cycle, Station is 3 so the conditions for the timer are met and it does not reset.

Operaghost · Sep 1, 2021

It looks like on the first rung after a 2-second delay it sets the DN bit and moves "1" into Station. Then the second rung sees a "1" in Station and immediately increments it to "2". Then the third rung sees a "2" and immediately increments it to "3". All that happens in one scan once the DN is set.

That's what it looks like the logic is doing. So, your Station is probably going from 0 to 1 and holds there for two seconds, then jumps to three.

What are you trying to have happen here?

EDIT: Others typed that faster than I did

. And unless I am mistaken, reversing the order of the last two rungs would still have it immediately go from 1 to 2 without any delay. It would then move to 3 on the next scan. Again without any delay.

OG

TheWaterboy · Sep 1, 2021

Hey Bit,
Reversing the bottom 2 rung now creates counts from 2 to 3 and then pauses. so that's diagnostic, but why wont it count 0...1,2,3 repeat. That's the goal.

plvlce · Sep 1, 2021

TheWaterboy said:
Hey Bit,
Reversing the bottom 2 rung now creates counts from 2 to 3 and then pauses. so that's diagnostic, but why wont it count 0...1,2,3 repeat. That's the goal.

Original is continuously counting 1,2,3... just all within the space of a single scan cycle.

EDIT: It's hard to help when we don't know exactly what your desired behaviour is. When do you want it to be pausing? Do you want it to go 1 PAUSE 2 PAUSE 3 PAUSE (repeat)?

drbitboy · Sep 1, 2021

TheWaterboy said:
Hey Bit,
Reversing the bottom 2 rung now creates counts from 2 to 3 and then pauses. so that's diagnostic, but why wont it count 0...1,2,3 repeat. That's the goal.

Oh, I assure you that station is counting from 1 to 2, then from 2 to to 3. you just never see the 1 because it is only at 1 for one scan.

Adding an [XIO PollCycleDelay.DN] before the original code might also work.

It looks like you want to

* poll, or at least assign a 1 to its blur.Poll, any station that is enabled i.e. has its blur.EnableStation with a value of 1, and continue polling that station for as long as its blur.EnableStation remains 1 (perhaps a poll assigns a 0 to its blur.EnableStation).
* When a station's blur.EnableStation is 0, move on to check the next station.
* after checking station 2 when its .EnableStation is 0, wait 2000ms.

TheWaterboy · Sep 1, 2021

The end goal is a driver for radio Polling. Each stations MSG and processing is its own program that performs an ADD when their read and write are completed.

The "enables" allow me to skip a station entirely if needed, otherwise if the MSG is going to fail it will hold the counter till it times out.

Opera: yes that what is supposed to happen, but the counter should reset once it reached 3.

PLVLCE: That sounds very plausible. How to get around that...

cardosocea · Sep 1, 2021

TheWaterboy said:
Hey Bit,
Reversing the bottom 2 rung now creates counts from 2 to 3 and then pauses. so that's diagnostic, but why wont it count 0...1,2,3 repeat. That's the goal.

You never start counting from 0... you recycle back to 1.

Increment the station number in one place per cycle. When you receive the feedback that the msg was sent and received a reply, move to the next. This is where an array with structs would look fancy and make the code simpler to write?

Operaghost · Sep 1, 2021

Your timer is staying locked in as True via the GRT. The timer needs to go false to reset and then get re-triggered.

OG

plvlce · Sep 1, 2021

You need your rung with the timer to be false for at least 1 scan cycle immediately following your counter incrementing.

EDIT: What OG said

TheWaterboy · Sep 1, 2021

plvlce said:
Do you want it to go 1 PAUSE 2 PAUSE 3 PAUSE (repeat)?

1,2,3 Pause, 1,2,3 Pause

plvlce · Sep 1, 2021

For a simple fix, how about just add XIO PollCycleDelay.DN before the timer?

EDIT: Beaten to it by drbitboy again I see.

TheWaterboy · Sep 1, 2021

OK I am pursuing the wrong idea then... under normal operation (EnableStation True) I want it to enable the series of x.poll bits in sequence.

The x.Poll bit is a public parameter of each program that enables MSG logic which would consume some scans. I see that trying to do this in a single ladder as a test appears to be impractical.

Why does this NOT re-cycle after delay

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