Vision120 - High Speed Input

[Guli]

Hi.

 

I am using a Vision120 V120-22-T2C controller.

I want to read Pulse from my Power meter Socomec Countis E21.

It hase a 100mS pulse duration, so the standard imput (I0) does not read it.

So how can i read the pulse so short?

I dont need a HI Spped counter, i need to read a contact with 100mS duration.

 

Thank You!

 

 

 

 

[viscoelastic]

For that short of a dwell time; I would use a high speed input. Even if the standard input could read it, you may have missed counts because it relies on checking each scan of the program. High speed inputs are independent of the scan.

You see opposed of using a high speed input. May I ask why?

[Guli]

49 minutes ago, viscoelastic said:

For that short of a dwell time; I would use a high speed input. Even if the standard input could read it, you may have missed counts because it relies on checking each scan of the program. High speed inputs are independent of the scan.

You see opposed of using a high speed input. May I ask why?

Hi,

 

is there any sample how to properly program a high speed input so it writes  1 to MB on rising edge of pulse?

 

[Ausman]

4 hours ago, Guli said:

It hase a 100mS pulse duration, so the standard imput (I0) does not read it.

100mS = 0.1 Seconds, so the really critical thing here is what is the off time.  Are you saying the pulse is 100mS with 50 ON and 50 OFF?  Or the pulse itself is 100mS ON.  In that case what is the shortest time it will be OFF?  If, for instance, the OFF time is 50mS then the plc can easily read this change of state situation on a normal Input.  Scan time on a simple program is measured in mS well below 10, often 1 or 2.  So you have a relatively long time for the change of state to be accurately read.  But that is why the question about OFF time.  If it is only a few mS, which I doubt, then you will need to use a high speed input, but even an OFF time of 10mS should likely be read OK.

If your program is simple and the OFF time is >10 like I have written about, and your plc is not reading the input change correctly, then you have something wrong in your wiring or your other input related interfaces. 

Your question about writing 1 to MB shows a need to have a good look at the help files about the various operands used in Unitronics, and how they are implemented in the ladder. 

cheers, Aus

[Guli]

1 hour ago, Ausman said:

100mS = 0.1 Seconds, so the really critical thing here is what is the off time.  Are you saying the pulse is 100mS with 50 ON and 50 OFF?  Or the pulse itself is 100mS ON.  In that case what is the shortest time it will be OFF?  If, for instance, the OFF time is 50mS then the plc can easily read this change of state situation on a normal Input.  Scan time on a simple program is measured in mS well below 10, often 1 or 2.  So you have a relatively long time for the change of state to be accurately read.  But that is why the question about OFF time.  If it is only a few mS, which I doubt, then you will need to use a high speed input, but even an OFF time of 10mS should likely be read OK.

If your program is simple and the OFF time is >10 like I have written about, and your plc is not reading the input change correctly, then you have something wrong in your wiring or your other input related interfaces. 

Your question about writing 1 to MB shows a need to have a good look at the help files about the various operands used in Unitronics, and how they are implemented in the ladder. 

cheers, Aus

100mS is the ON pulse duration. The device is a Power meter that pulses every 1W/h.

The max. load on the Power meter is about 8kW. So on max load it pulses with 2,22 Hz. 

I found out, that time to time a pulse is read by PLC.

That means, the scan time is too slow to read my pulse.

OK, back to my question, is there any sample or can anyone write me one, how to read pulse with High Speed Input.

 

Thank you!

[Flex727]

44 minutes ago, Guli said:

That means, the scan time is too slow to read my pulse.

Seems unlikely. What is the scan time? (Go online and check the value of SI 0)

[Ausman]

5 hours ago, Guli said:

OK, back to my question

Actually you need to answer MY question about off time.  You do understand that 2.222222...... Hz is only a little quicker than 2 x 100mS pulses per second, don't you?  You're not thinking in terms of KiloHz? 

So again, we get to what is the off time?  On your full load specifications, if the on time is strictly a 100mS pulse, then the off time is approximately 350mS.  Both of these intervals are easily read by a normal input.

cheers, Aus

[Guli]

Hi,

my scan time SI 0 = 6mS

The pulse is constant 100mS ON, the OFF time differs acording to Power consumption.

So normal input should read 100mS pulse, why does it read pulses only from time to time?

When i connect a signal generator, the PLC reads pulses up to 80 Hz on the same input as i use with the Power meter.

 

 

[Flex727]

7 hours ago, Guli said:

why does it read pulses only from time to time?

I have written programs for various pulse totalizers and never had a problem detecting the pulses on a regular digital input.

Perhaps you have a logic problem. Post your program.

[Guli]

HI,

OK, my Power meter has a light indicator that pulses every 1W/h.

I finaly found out, that the pulse outpoot, connected to my plc is pulsing every 100W/h and not every 1W/h.

So i get an 100mS impulse every 100W/h and the plc is reading it normaly.

Thank you for your anwsers, and sorry for the inconvenience.

[Flex727]

No inconvenience, and thank you for reporting back with the answer you found.