nicepal

CJ1W-ETN21 Detection

4 posts in this topic

To all the gurus.

We have a project now that is using CJ2M PLC. However some hardware is using 1 piece of ETN21 card while some machines are using 2 cards. Programs sequence is quite similar. However Customer wants us to be able from program side able to detect if there is 1 card presence or 2 cards presence.

 

Not sure if there is certain bits or memory in PLC that program can tap to "detect" number of cards that is presence.

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You could have both modules registered in the I/O Table and if one is missing, there will be a non-fatal (PLC will keep running) error 

A402.03 will be on when one is missing and then the bit in A427 corresponding to the unit number (dials on front of module) that is missing will be on:

5db06700d1f52_CPUBius.png.ab08315e8ccd9d

 

So, if you have 2 ETN21 cards registered in the I/O table as units 0 and 1, if unit #1 is missing then A402.03 will be on and A427.01 will also be on.  

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Michael,

Thanks, this sound great.

Just that the scenario is 

1 - We have 2 batches of machines

2 - Batch 1 is using 1 card

3 - Batch 2 is using 2 cards

4 - 2 cards communication seems to be more stable as compared to 1 card. Just that software portion is a little different for the 2 machines though they are identical.

5 - Customer request is to keep program the same. Use a method to "detect" if there is 1 or 2 card exist, then run different portion of programs for this. Instead of keeping 2 program version.

 

But hearing you saying declare 2 cards in I/O table but 2nd card physically not installed will generate a non-fatal (PLC will keep running) error. Maybe we can use this "error Bit" to determine if the 2nd Card is present or not.

 

Thanks in advance. Shall update again when tested working.

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15 hours ago, nicepal said:

But hearing you saying declare 2 cards in I/O table but 2nd card physically not installed will generate a non-fatal (PLC will keep running) error. Maybe we can use this "error Bit" to determine if the 2nd Card is present or not.

Yes.  This is my suggestion.   Create IO table as if two cards are present and then use the card missing error to enable the single card program.

 

If you were to do separate IO tables for the 1 card method or the 2 card method, then you would already know which configuration you had and would not need to auto detect, you could manually activate program for 1 card or for 2 cards when installing it.  

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