CP340 RS232 connection Siemens PLC to Sartorius Balances

Hello,

I have 3 balances connected on RS232 at very low speed (2400bps).
All 3 make good communication.

But, after a day or so, 1 or more connections can be messed up.
The RXD led's are still blinking at that moment, but no valid telegram of 16 bytes from the balances (telegram messed up, CR and LF at wrong place).

Restarting the CPU solves the problem temporarily...

What could be the cause ?

Thanks,
Combo

Hi! I don't know your hardware but do still have som queries.

Is the CR/LF the telegram end sequence?

Could it (the mess) be caused by not suited characther delay time?

Do you poll for data, or are they sent continiously from the balances?

Do you call a receive block continiously - to empty the receive buffer? And with which frequency?

Kalle

3 balances on RS232???? RS232 is a 1:1 protocol?? How did you make a multidrop connections?

Hi

3 CP340's

Homer_BL said:

3 balances on RS232???? RS232 is a 1:1 protocol?? How did you make a multidrop connections?

Click to expand...

))

ok

Hellow

Is the CR/LF the telegram end sequence?

Click to expand...

Yes

Could it (the mess) be caused by not suited characther delay time?

Click to expand...

What do you mean by this ? The telegram is ended with CR/LF (Hex: D and A). My setting is: On End characters (2 chars) CR + LF. In the transfer tab I setted CTS.

Do you poll for data, or are they sent continiously from the balances?

Click to expand...

No polling, the balances send their telegram every second (very slow). When I set the balance to a more frequent send, then it get messed up within 10 seconds, so now I've chosed to send it very slowly. This can be done by set: Very unstable print, in that case it refreshes the display and the serial port much slower. So no polling.

Do you call a receive block continiously - to empty the receive buffer? And with which frequency?

Click to expand...

Yes. It is called in OB1, with a 319CPU at 1ms cycle time...

Thanks for your comment,
Regards,
Combo