1734-232ASC/C ASCII Module – Data Being Sent After PLC Power Cycle

[LochRaven]

Does anyone know how to inhibit the 232 module from sending data during PLC power-up? To send data during normal operation, the Transmit Record Number needs to change. The Transmit Record Number is not changing during power-up. When the PLC powers up, it appears that the data is being sent on first scan.

Thanks for your help!

 

[Ken Roach]

Welcome to the PLCTalk forum community ! That is an excellent question.

My first instinct is to use the power-up handler and/or the S:FS bit to put a zero into the Transmit Record Number.

I would have to test to find out if zero is special on the 1734-232ASC. If you are in ordinary run mode and the Tx Record goes from 100 to 0, for example, does it transmit ?

Is this a 1769-L1x where the 232ASC will power cycle along with the controller, or is the 232ASC connected via a network adapter ? Does the network adapter power cycle along with the PLC ?

 

[LochRaven]

Thanks, Ken.

It's an expansion module on a 1769-L18ER-BB1B. So, the module will power cycle with the controller.

I'll try your suggestion tomorrow morning with resetting the transmit counter to zero.

Thank you for your time!

 

[LochRaven]

Ken,

Your suggestion worked; I loaded a zero into the Transmit Record Number on first scan.


Thanks for your help!