Serial communication PLC - x-ray

[magneto0212]

Hello!

I have a problem in communication between Siemens 400 PLC and x-ray for luggage examination.

I am communicating with x-ray via CP441 module, point to point and I use bsend and brcv blocks in TIA Portal.

First day when I tried to establish connection I managed to send data to x-ray (what I can see on it) but couldn't recieve and recieve block was constantly in error, showing error code 1 what means something is wrong with communication. After I restarted x-ray error was gone and I could recieve data from it.

My problems begin next time when I came to work with it and I cannot at all recieve data (I send normally), error code 1 is constant at brcv block and when I tried to restart both x-ray and PLC several times didn't help. X-ray is setup so, that when it recieves a code from me automatically sends back to me and then I see that both RxD and TxD are blinking.

Now I'm waiting for xray technicians to get a conformation from them that x-ray is functioning normally.

What is your opinion, could be something wrong on my side, because I don't have many experience with Siemens equipment and software?

 

[gclshortt]

Communications was established and working. This will rule out the program itself. I would look at the cable and the grounding on the RS232C cable that you are using. Ensure that the shielding wire is only connected to one side of the cable. (FG)

If it is a grounding issue, you may need to switch to optical isolation.

Just a thought.
Regards,

 

[magneto0212]

Communications was established and working. This will rule out the program itself. I would look at the cable and the grounding on the RS232C cable that you are using. Ensure that the shielding wire is only connected to one side of the cable. (FG)

If it is a grounding issue, you may need to switch to optical isolation.

Just a thought.
Regards,

Thanks for opinion, I just forgot to mention it's RS422 standard, but I suppose the things for the cable nad grounding should be equally worth as for RS232?

 

[gclshortt]

Yes it will be similar for RS422.

Regards,