Mitsubishi doesn't have off-delay timer

[longshot]

In Mitsubishi's PLCs, there is no off-delay timer. If you need one in your program, how do you get one ?

 

[ganutenator]

we don't need no stink'n off timer

Most of the off delay timers I have seen (I haven't worked with the Mitts) can be created by using an on timer. Usually just by reversing the input conditions to the timer (not each individually, but by taking the NOT of all the conditions powering the off timer), and taking the NOT of the Done bit, and voila.

 

[Gerry]

Caveat

One thing you need to remember when simulating off-delay timers is that they initialise to the 'done' state whereas on-delay timers don't - just like the real-world pneumatic timing relays. This may not be a concern in every instance, but one should be aware.

 

[Pierre]

Off Delay or On Delay timers, it's only a mather of logic. What Mitsu really does not have is a Retentive Timer. Even in there fantastic Q serie, they still don't have it. So where stuck with using counters.

 

[Tom Jenkins]

Here is logic that the guys from AtomationDirect.Com gave me a few years ago - they don'thave an off delay timer either. I'm sure you can adapt it for your PLC.

| Input_for_timing
|      X0
|------|/|--------------------|TMR    T0
|                             |K10
|
|      X0                      Y0
|------| |--------------+-----(OUT)
|                       |
|      Y0        T0     |
|------| |-------|/|----+

 

[Kim Gold]

Here is an example of simulating an off delay timer.
See attachment.

XIO B3:0/0 TON T4:0 0.01 100 0
BST XIC B3:0/0 NXB XIC B3:0/1 BND XIO T4:0/DN OTE B3:0/1
XIC B3:0/1 OTE B3:0/2

 

[longshot]

Thanks for all the replys

The examples gave by Tom and Kim are similar, simple and useful.

To Pierre,

There are some retentive timers in new models, even in small systems like FX2c and FX2nc.

 

[john paley]

My AB plug for the day--

It's interesting that Kim gave her example using Rslogix, where such code would never be required.

Sorry, just couldn't help it.

 

[Tim]

Pierre

Off Delay or On Delay timers, it's only a mather of logic. What Mitsu really does not have is a Retentive Timer. Even in there fantastic Q serie, they still don't have it. So where stuck with using counters.

Pierre,
I'm not absolutly sure, but I was just messing with an old AOJ2 and was able to set up a retentive timer in the parameter settings.

 

[Terry Woods]

This is much the same as has already been posted, but, with a little twist...

insert fig-1

You can then use "Input-1 (Off-Delayed)" as Input-1 in an Off-Delayed fashion. It doesn't have to be tied to a specific Output.

In fact, you can apply Input-1 to several Timers as in...
"Input-1 (Off-Delayed-1)", "Input-1 (Off-Delayed-2)", "Input-1 (Off-Delayed-3)", etc.

Kind of a shut-down sequencer on the cheap!?

insert fig-2

If you use an On-Delay Timer to provide the Off-Delay, I don't see how the Timer Bit can be initialized as DONE! Unless the Preset Value is Zero!

insert fig-3

There is a problem that pops up once in a while...
If the Timer Value is, or can be, set by the operator and the operator happens to set the Preset Value (TCP) to Zero, the Timer Output Bit is set immediately! This can be remedied, in some PLC's, by simply adding the Timer Conditional Bit AFTER the Timer as well as before.

In others, where the rung stops at the Timer, the same effect can be had by...

insert fig-4

Now, if the Timer happens to be set to Zero, by the Operator or the Program, the Timer effect will not occur until it is time to invoke "Condition-1".

And, Pierre, as far as Non-Retentive Timers... how about copying the Timer value to Non-Volatile memory every scan? Yeah, I know, it's an extra step to be taken, but... so what? You might lose a little bit of time between scans. Worst case is the loss of one Scan Time. That might or might not be critical...

 

[ganutenator]

I am a little confused at how difficult everyone is making this, but maybe it is because I am confused.

I was asked by a customer to not use any TOF's in my PLC5 program. I went through the program and NOT'd the inputs to all my TOF timers and used the XIO instead of the XIC on the Done bit and voila, everything worked perfectly.

Now, maybe all that pot I smoked since I did this has jarred my memory or something. just kidding

 

[Gerry]

If you use an On-Delay Timer to provide the Off-Delay, I don't see how the Timer Bit can be initialized as DONE!

I should have said "initialises to the timed-out state". Apologies if I confused anyone. When a TOF is timed out, its done bit is off.

The posted examples will emulate this.

I went through the program and NOT'd the inputs to all my TOF timers and used the XIO instead of the XIC on the Done bit

If the timer input bit is off (rung true) on power-up or first scan, then the XIO of the TON's done bit doesn't open until the preset time has expired. After this initial interval, the emulation is fine.

I was asked by a customer to not use any TOF's in my PLC5 program.

Sheesh!

 

[Gerry]

And, Pierre, as far as Non-Retentive Timers... how about copying the Timer value to Non-Volatile memory every scan?

In AB-speak, a retentive timer (RTO) operates like a TON except that when the rung goes false, it holds rather than resets. When the rung goes true again, the timing carries on from where it was. There is a separate instruction for the reset operation.

In AB PLC's all memory is non-volatile. Some parts get initialised on power-up depending on how they are addressed in the program.

 

[eld101]

Off Delay or On Delay timers, it's only a mather of logic. What Mitsu really does not have is a Retentive Timer. Even in there fantastic Q serie, they still don't have it. So where stuck with using counters.

The Q series most certainly does have a retentative timer. Go to PLC Parameters --> Device Tab. In the list you will see Retentative Timer (ST) You have to allocate them here.

 

[rdrast]

The Q series most certainly does have a retentative timer. Go to PLC Parameters --> Device Tab. In the list you will see Retentative Timer (ST) You have to allocate them here.

Pop on back to 2002 and mention that.