logix 500 timers vs studio 5000 timers

[Mgw1970]

I recently did a program conversion from logix 500 to studio 5000 and when machine runs it depends on two ton instructions to keep the machine in synch and watching the timers accumulate T2-T1=difference on the logix 500 program the difference stays pretty consistent while on the other hand studio 5000 is all over the place I used a divide instruction to equal the 0.001 to 0.01. I've tested the program using slc500 emulation with timers acting as the synch sensors and on the studio 5000 using a 1969-L33er and a Micrologix with a flash timing program to act as sensor inputs of the compactlogix to simulate the routine using and just like slc500 I go same time settings on the micrologix to simulate sensor 1{T4:0 & T4:1/pre=20} Sensor 2 {T4:2/T4:3/ pre 20}. But monitoring the program the difference is different for one hardware to another. Has anyone had this issues?

 

[joseph_e2]

It's not super clear what you're seeing or expecting. Can you share the code? At least an online screenshot showing the code that's acting differently in the different systems.

 

[Mgw1970]

The timer.acc from the old system are more consistent and the new system the timer.acc are not consistent. Normally the timers sit at 63-64 which have a difference of 1-2 a dnd the new timers are from 20-70 which have wide spread difference. On the machine

 

[Robb B]

The processors lying underneath the programming both manage timers very differently, there are many conversations on this site about how timers function and their (in)accuracy. You've also got differences in the hardware between 5000 and 500 platforms, scan times, I/O update cycle differences, etc.

 

[5618]

I don’t fully understand what you’re doing, but maybe this is part of what you see. The CompctLogix timers all have a timebase of .001 seconds. If you’re seeing variation of 20 to 70 mS, depending on the application that sounds reasonable for standard I/O.

Each input module has a RPI value for the data exchange rate between the module and the controller. 20 mS is a pretty common rate for basic I/O which can account for 20 ACC variation for each trigger. If you’re running the timer in a periodic task, that period will also affect timer ACC values since the timer is only scanned as often as the task.

Right click on the task and select monitor. There you will see scan times and intervals. You should not expect to see ACC values tighter than the task execution plus the IO rate.

 

[jaden]

Depending what is involved in your Division steps, I'm wondering if you might be getting rounding errors or values being truncated.

 

[JaxGTO]

When converting SLC programs with critical timing (in the SLC) it's best to put the program in a timed execution routine that runs closer to the SLC scan time. Like 50ms. I have found that converted programs that had critical timing don't run very well in micro second scan time environment.

 

[drbitboy]

What is the scan cycle time of the RSLogix 500 PLC(s?)? It should be available in system word S:4, and the meaning will be dependent on the PLC model (e.g. 10kHz ticks in a MicroLogix 1100).

What is the scan cycle time of the RSLogix 5000 PLC(s?)? I have no idea where to find this.

Also, some idea of what you are trying to keep in synch would help, or post the code (PDF preferred) as @joseph_e2 requested in the first response. The language of your two posts in this thread make little sense, at least to me, e.g.

Normally the timers sit at 63-64 which have a difference of 1-2 a dnd the new timers are from 20-70 which have wide spread difference. On the machine

63-64, 1-2, 20-70, units of what? What does this even mean?

 

[Mgw1970]

I'm trying keep a knife cutting dough balls in synch with a proofer.

 

[drbitboy]

I'm trying keep a knife cutting dough balls in synch with a proofer.

Those images are not "your code." Post full PDFs of both, along with a description of the process model used by the PLCs, if comments are sparse. Otherwise no one has a clue what is happening, and we can only make guesses, like this:

Also, and again, what are the scan times of the different PLCs? If the 500 scan time is order 10ms, then a 0.01s time difference between the timers is achievable. If the 5000 scan time is an order of magnitude longer (100ms) or more, then the instants when the timer accumulator values are sampled could vary widely.

 

[Mgw1970]

Thanks for the responses, I thought I was clear on my problem. I added the studio 5000 knife synch routine, and the slc 5/04 synch routine but I have to break it it into to different post because of size and the amount of attachments.

 

[Mgw1970]

the rest of slc 5/04 synch routine

 

[drbitboy]

so what you are saying is that T4:47 is used to measure the approximate time duration from one Knife Prox event (rising edge) and the next Knife Prox event, and T4:48 is used to measure the approximate time duration from one Proofer Prox event and the next Proofer prox event.

And you expect any [T4:47.ACC, T4:48.ACC] pair of those duration measurements, taken near the same time, to measure the same amount of time, to within some tolerance.

Is that correct?

 

[Mgw1970]

Yes you are correct, and any large difference between the two t4:47&,t4:48 it changes the speed of the proofer.

 

[Ken Roach]

In many applications, a CompactLogix is going to run faster and more precisely than an SLC-500. But we don't know the specifics of your system; a ZIP file with both programs would be best.

One major difference between SLC-5/0x and CompactLogix is that the SLC-500 I/O is synchronous with the program: Inputs are read at the beginning of the program, and Outputs are written at the end. There are options for configuring some SLC-500 family Input modules to execute interrupt routines, so your LAD11 might be executing when a specific input goes true on the Input module in Slot 4.

CompactLogix, unlike ControlLogix, doesn't have fast input interrupts. You should look at the "RPI" value for the discrete input module you are using for these inputs.

Another important difference between SLC-500 and CompactLogix is that the SLC-500 had only 1-second and 0.01-second timebases for its timer instructions (the MicroLogix had a 1-millisecond timebase option).

ControlLogix and CompactLogix timers always use 1 millisecond increments for their PRE and ACC values.

You will see differences of 10x in the accumulated values between the SLC and CompactLogix controllers. A difference of "1 or 2" in the SLC will be a difference of "10 or 20" in the CompactLogix.

There is very probably a better way to do your synchronization and time captures on the CompactLogix. The underlying system clock on the CompactLogix is in increments of microseconds, not milliseconds or hundredths of a second, and you can capture it with the GSV instruction.

It looks like you might be using analog modules to command VFDs or servos as well, so there could be some considerations you need to examine with the scaling of the different kinds of modules.

Yours looks like a fun project; please post more if you get a chance !