CPM1A Activating a Timer

[OdinPT 0]

Hi people, I have a cpm1a and i need to activate a timer with a impulse only, but the timer condition says: " A timer is activated when its execution condition goes ON and is reset (to SV) when the execution condition goes OFF. " As i said i just want to give an inpulse and then make the timer run 2 seconds and activate... What i need is to recieve an input and make a delay of 2 seconds and activate an output, how can i do this ? Can someone help plz? Thanks.

[ECSI 17]

Try this... Edited 4 Apr 2006 by ECSI

[OdinPT 0]

Hi, Thanks for the help, what if i want to use the end of the timer to do the "reset" ? I only can use one input and i want to do the pulse input more times. Is there a way to use the end of the TIM to do the reset? After The 2 Seconds i can use the Pulse again. Thanks Edited 4 Apr 2006 by OdinPT

[gtsuport 61]

Based on the sample circuit, the problem with using the timer to reset the circuit is that the "output" would only be on for 1 scan (pulse). How long do you need the output (10.00 in sample) to stay on?

[OdinPT 0]

Hi, Not more than 60ms.

[gtsuport 61]

Based on the "typical" CPM1 scan, it would probably only be on for 1 - 2 ms. If the unit has relay outputs, you may never see the actual output turn on (relay pickup time). Will this work for your application? If not, you will probably need another holding circuit with another timer to maintain the output for the desired time value. The above sample could till grab the next pulse and begin the delay during the holding time on the second timer. Hope this makes sense. And I hope it will help.

[OdinPT 0]

Yes but I need a bit more time to do the output activation, I suppose isn’t going to work…. I am trying to find the solution to the following problem: I have 2 Light Sensors Photocells a Rejection Arm (something that pulls the object out) and a carpet that moves in cycles (isn’t always running it runs after seeing an object in S1, for example if an object is S1 the carpet moves fast until the end, passing through the conditions). The objects come in a carpet from right to left and I want to ensure that if the Object enters in LS1 and is to be rejected LS2 can’t be activated or if the Object enters LS1 and is not to be rejected it passes through LS2. My main problem is that I have to validate these conditions in a carpet cycle and is Really fast like 10000 objects /hourK. I’m using 3 memories one for LS1, RA and LS2 I try to validate them when S1 receives other object and I do the reset before it reaches LS1, that’s why I was asking how to use a timer only with one impulse the S1 impulse the example for the 2 seconds was to try to comprehend how would it work. LS2 RA LS1 S1 How can I do a validation in so fast cycle? What is the best solution… really timers don’t seem to be very good… but the velocity between LS1 and LS2 is always the same, fast but always the same. I’m sorry to expose the problem this way but I am really in need of help.

[gtsuport 61]

Sorry OdinPT, but I think we are back to the language thing again Let me see if I understand. You already know if the part entering the carpet on the right is good or bad. If the part is good, when S1 is activated the carpet will start and you should see a signal at LS1, then at LS2. If the part is bad, when S1 is activated the carpet will start, you will see a signal at LS1, but will not see a signal at LS2, because the Rejection Arm should have removed the part. Also what do you mean by validation? You need to confirm that the correct sequence actually happened. Is this what should happen? Sorry to not understand your original post.

[OdinPT 0]

Hi, It is true my english is very bad... And to explain a situation it gets worse. You don't have to ask sorry for nothing Back to the problem, The carpet is allways running and yes i allready know if the pack is good or not when it reaches S1 it validates good or not. When the S1 cell is activated the carpet simply goes on untill the end and i want to validade the condition of "Object good and has been removed" or "Object bad and hasn't beem removed" before other object reaches S1. When i mean validation i mean to send a signal to the output if one of those 2 conditions happen before other object passes. (and they pass really fast...) As you said : If the part is bad, when S1 is activated the carpet will start, you will see a signal at LS1, but will not see a signal at LS2, because the Rejection Arm should have removed the part. This is my main problem... I'm thinking on using a Timer activated when the object enters the LS1 then i wait 30ms to see if the LS2 is activated... if is activated and the object has an error it sends a signal to the output. But then i need to restart the LS1 and LS2 memories... and don't know how... sinse after 30ms other object is allready in S1. Oh my god

[gtsuport 61]

I need to think on this one! What is the distance between LS1 and LS2? What is the speed of the carpet? I think yesterday you said about 10000 parts per hour. That would indicate one part every 300ms. I will give this some thought and hopefully can figure something out.

[OdinPT 0]

Well if is to do some calculations.... The object size is about 10cm, the distance between the photocells is about 30cm and the carpet yes 10000/ hour. I don't see other way to do this without the timer... i thought on 30ms... i use TIMH with #30 after LS1 is lit but i have sometimes some errors i think is because the TIMH and the restart of the memories... Im new on this PLC world i had some lessons but.... well... In real situations is a lot diferent Edited 5 Apr 2006 by OdinPT

[BobB 58]

If you are going to use TIMH there are limitations on where in the timer map you can use the instruction. You have to use timers 000 to 003 or the timer will not be accurate if the scan time is over 10ms. This is explained in the manual.

[OdinPT 0]

Today i couldn't try the timer situation.... Lets see if tomorrow i have the PLC to do some experiêncies. Thanks for the help you all