millisecond timing

guy's

which if any plc's have a millisecond timer . direct logic or allen bradley , siemans ,modicon ?

You need to separate out preset entry from actual time resolution.

The AB ControlLogix and CompactLogix plcs, for example, have a 32-bit timer preset entry in microseconds. However, you will only get control resolution down to your scan time. In other words you can enter a 1 microsecond preset but the timer will simply delay the action 1 scan and your delay will be whatever the scantime is for the previous scan. So just because you can enter it doesn't mean you can control to it.

Keith

Has to be all of them!

1 second=1000ms , so how muuch smaller a brand can go will be interesting to know.Any brand with 10 pico second !!

Hi,

A few months ago, I made a high speed data logging project.
It was based on an AB Control logix.
The processor was L63
It had high speed analog acquisition boards.

The project was designed to run at 500 micro seconds (0,5 ms)

I Think this reaches the limits of PLCs (any brand)

If you need to run faster, you have to go to industrial PC with I/O boards.

If not enough, you'll have to go for a VME rack.

Antoine.

Milliseconds, not microseconds for Logix. Unless you use the seperate boolean processor.

kamenges said:

You need to separate out preset entry from actual time resolution.

The AB ControlLogix and CompactLogix plcs, for example, have a 32-bit timer preset entry in MILLIseconds. However, you will only get control resolution down to your scan time. In other words you can enter a 1 MILLIsecond preset but the timer will simply delay the action 1 scan and your delay will be whatever the scantime is for the previous scan. So just because you can enter it doesn't mean you can control to it.

Keith

Click to expand...

Sorry about that. My bad. I was just playing with GSVs to the WALLCLOCK and confused myself. Thanks rdrast.

Keith

In one application I used the Keyence KV series. It had millisecond preset timers and, more importantly, had sub millisecond scan times. You may want to check it out.

Which (if any) PLC's have a millisecond timer? Direct Logic, Allen Bradley, Siemans, or Modicon?

Click to expand...

Manmeetvirdi came close to answering the acutal question.

Automation Direct appears to go only down to 0.01 seconds.
Allen Bradley (RSLogix500) offers the 0.001 second timer (1 milisecond.
Simens Step 7 has a 1 millisecond timer
Omron CX has a "Very High Speed" 1 ms timer
Idec Windldr has a 1 ms timer.

I don't know about Modicon.

In most models, whether you can actually use timers in the 1 ms range depends on the scan time of your program.

Lancie1 said:

Allen Bradley (RSLogix500) offers the 0.001 second timer (1 milisecond.)
...
In most models, whether you can actually use timers in the 1 ms range depends on the scan time of your program.

Click to expand...

I would like to add that there are a limited number of processor models that support the .001 millisecond timebase in RSLogix500. I believe all of Allen-Bradley's RSLogix5000 programmed products support it.

And, some PLCs offer instructions that will allow you to make use of their highest precision timrs via special instructions like interrupts, even when the main routine scan time is longer.

The GE RX3i PAC (Programmable Automation Controller) has 1, 0.1, 0.01 and 0.001 second timers.

Edit...
I guess that I should also address scan time. The average scan time for an RX3i with several hundred rungs of ladder logic is around 5 Ms, but you can tweak the sweep modes if you need to.

Regards

Siemens High Speed Boolean Processor

The Siemens FM352-5 will give you Input / Output and Timing resolution of 10 micro-sec. I used it to to generate Pulses with operator defined periods of 1 - 2000 ms, on a 1 ms raster and the accuracy at the lower end of the spectrum was 2 - 3 micro-secs. I didn't have suitable equipment to measure the accuracy at the 2000 ms end of the scale, but it seemed to be pretty good.

This is a Xenix FPGA based 12 pipe parallel processor with a 1 micro-sec cyle time. One important point to notice, although I used it in conjuction with a 317-2DP CPU, this is not essential. It can be used stand-alone. At around 1000€ it's not even that expensive for this sort of performance.

Only negative point is that the learning curve is pretty steep, but my experiences with the beast here will help you through the worst traps.

The AB Micrologix 1100 let you use millisecond resolution on its timers. You can get scan times in the 1.5 to 3 msec scan times with small programs, therefore your true resolution will be that of the scan time of the program. I've also heard that some of the GE Fanus has some controllers with very fast scan times.