Rslogix 500

Dani610

Member
Join Date
May 2018
Location
Adelaide
Posts
33
Hello All,

I have two questions.

1- I am using two msg instructions in plc2 to read two different msgs from other plc1 so i was wondering that if it is possible to use a 1 msg instruction or any other simpler way.

2- it is very silly but since i am new to this so question is i have a rung say rung 2 that will activate only when a condition at later rung say rung 7 goes true, when rung 7 goes true it does wait for next scan rung 2 goes true at the same time what i can do about that.

I am using AB ML 1400, Rslogix500
 
1- I am using two msg instructions in plc2 to read two different msgs from other plc1 so i was wondering that if it is possible to use a 1 msg instruction or any other simpler way.

Does it work? if yes then maybe just let it keep working and just document it so later someone or yourself can understand what its doing, having two maybe better than one... if you have one large message it maybe harder to understand


2- it is very silly but since i am new to this so question is i have a rung say rung 2 that will activate only when a condition at later rung say rung 7 goes true, when rung 7 goes true it does wait for next scan rung 2 goes true at the same time what i can do about that.


How about move the rung 7 logic above rung 2 logic... then 7 will be scanned first, there are also immediate output instructions that you can use if you need the logic to change before the scan

But this is hard to say one way or the other without seeing the logic and knowing what you are trying to accomplish
 
The short answer is, don’t know without a lot more detail on what it is you messaging. The long(er) answer is it depends on what you’re messaging. If the data you are messaging can be (or is already) grouped together so that it can be sent as an array then you could use one message instruction however if it’s not already grouped together it might be easier just to use two message instructions that it would be to rewrite you logic to move the data around just to change from two to one message instruction. In other words, don’t know without a lot more detail.
 
Does it work? if yes then maybe just let it keep working and just document it so later someone or yourself can understand what its doing, having two maybe better than one... if you have one large message it maybe harder to understand

Yes I think i will keep it that way





How about move the rung 7 logic above rung 2 logic... then 7 will be scanned first, there are also immediate output instructions that you can use if you need the logic to change before the scan

But this is hard to say one way or the other without seeing the logic and knowing what you are trying to accomplish

I have attached a picture of logic below it is a push button when I press the button first time my output(B3:1) goes on in both the rungs(rung 2 and rung 7). what I want is when i pgive input for first time only rung 7 B3:1 goes on and when i gice again then rung 2 B3:1 goes on.

For this purpose i have used GEQ in rung 2 so alarm should wait once the output is on it should not goes on when the output goes on for first time.

Thanks

Un4.jpg Un5.jpg
 
Last edited:
The short answer is, don’t know without a lot more detail on what it is you messaging. The long(er) answer is it depends on what you’re messaging. If the data you are messaging can be (or is already) grouped together so that it can be sent as an array then you could use one message instruction however if it’s not already grouped together it might be easier just to use two message instructions that it would be to rewrite you logic to move the data around just to change from two to one message instruction. In other words, don’t know without a lot more detail.

Yes they are different files i think i'd keep it that way or it will make it more complex

thanks
 

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