Richard Webb

M8013 is the 1 second cyclic relay.

I won't laugh, I'm an old man too. I'm just trying to figure out what you are trying to do. With the i second pulse, you can get that with the special register M8000's. Won't need any timers. If you could expand on waht you want, or come up with a small ladder example of what you are trying to achieve, I'm sure I could help you.

Hi Moggie, thanks for all your help, I have sorted it. The pulse from the board was a strange one, got it switching a solid state relay and SSR to X0, all fine now. Thanks again.

Okay, I really give up now. Tried a freewheeling diode, no change. The manufacturer gave me access to the unit. I have to take the pulses up to 1 second before the PLC responds, which is useless. Minimum I can go is 120msesonds, no chance of the PLC even seeing that. I really give up now. Going to Plan B.

Hi Moggie, I have since connected X0, X1, X2 and X3 to the four valves. It works after a fashion, it will see a pulse now and again, but it's not reliable enough to put into service. I do not have an oscilloscope, however, one of the contractors on site has said he will bring one in tomorrow for me to check the length of the pulse. However, I'm sure it's a bit too quick for the PLC to read. What would be the minimum in msec's that would work? According to the manual, it appears 10 msec seems to be the minimum. I have to come up with some solution. I'm looking at trying to get a Weidemuller  MCZ TO 24V/150MS MODULE. It will see a minimum of a 3.5 msec pulse and hold the output for 150 msecs. Just might have a problem with availability. Projects can be problematic most of the time.

They do not alarm for the reason I'm looking for. They are mostly for differential pressure alarm etc. All I want is when the unit fails. The chap that adapted them for me advised the only way to get what I wanted was the route I'm trying. Not sure what I'm going to do.

Been really busy with other things. However, this problem is still stopping progress with the project. Same PLC that I had on test at home. I will post a picture of the unit I am trying to get the alarm working. There is 4 solenoids that pulse to clean filters on silos, I am using the 5th output as an input to the PLC. They are 24 Volt DC outputs to the coils. The 0 Volts is common to the whole lot. According to the specs of the unit, the pulse should be 20msec. I can't verify that. Any help would be great!

I'm really at a loss now. Had it on test all day at home yesterday with a cyclic timer, perfect. Put it back in the controller today, same thing. The input will work at times, and then nor. Y0 does turn on when X0 sets M0. What I don't' understand, when I look at the programme "Online Monitor". I actually see X0 go blue, but doesn't pulse M1. What is that about. However, because the time is K2400, it does hold up for a while, however, M1 doesn't reset the time all the time, only now and again. I give up!

That's exactly what I want. I only need T0 to time out if there are no pulses. Than Y0 turns off and the alarm in my Loading Panel is activated and I close the inlet valve.

According to the specs on the controller, it's 20ms. I have it connected correctly. I have brought both PLC's home and running them again all day. No problem at all. I even thought that the pulse from the controller might not peak at 24 Volts DC, so I tried it a little while ago with 12 Volts DC, still works every time. I am using a cyclic timer, so I can't say exactly the duration of the pulse I am putting on it at home, but it's really quick, works every time. I have downloaded GX-Works 2, have reinstalled it on both PLC's, so they are recognised as FX3S units. I'm at a loss. I will try them tomorrow again and will install GX-Works2 on my laptop at work and see what the hell is going on. It's a simple programme, so I can.t see scan time being a problem. Even if it misses half the pulses it will still work. The S/S is definitely connected correctly. 0 volts and X0 +24V. What bothers me it did work when I first put the PLC in the controller. I'm grasping at straws now.

Hi Asad, Thanks for the info on GX-Works2. I don't understand how to reset the timer after a cycle. What I don't get, it worked fine for hours at home, then when I put it in the unit at work, it stopped working. That's what confuses me.

Thanks for the reply guys. Forgot to say I can see the X0 input led coming on with every pulse. I didn't have my laptop with me at work on Friday, so couldn't debug it on the controller. I will attach the programme I have written for it, really simple, so confused where it's falling over. Hopefully you can spot the stupid mistake I'm making.

I have a problem with PLC not seeing the input. I am using a FX3S, however, because I still am using GX Developer, it will only recognise it as a FX1N. My problem is I did a small programme for an alarm on a "Blow Down" system for filter cleaning on Silos. Tested it at home with a cyclic timer, everything working fine. Got the controller this afternoon and found I had a problem. It looks like it's not seeing the input to reset the time out timer. Worked for a while, then fell over. Using X0. The switching time I am monitoring is 20msec, which I thought would not be a problem. This is going to be a major setback for me with this project. Eight of these controllers. Any help would be great.