Communication problem with MODBUS RTU

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Thread Starter

sonu

I have a XBTGT2110 and a TWDLCAA24DRF CPU that does not want to communicate. The XBT gives the error "No reply from PLC within Timeout period." I'm using MODBUS RTU communication from the XBT. Please send me any info you might have on this problem
 
What are sure your Modbus settings on the Twido match the settings of the HMI?

Baudrate, parity... Especially I found the Twido default values for the time between frames are often not matching my Modbus Master.

Do you use the programming port as modbus port or an optional port? In the last case, is the port correctly inserted?

Have you check your end of line resistors, your isolation... ?
 
R

Robert Willis

The two most common causes for this are the use of a incorrect cable or the serial port configuration of the display or PLC are incorrect.
 
> The two most common causes for this are the use of a incorrect cable or the serial port configuration of the display or PLC are incorrect. <

I concur.

Now the next question which port are you connecting to?? If you are connecting to port one then set it to 9600, 8, 1, and none*

*NOTE the PLC must be set to none on port one.

I have spent many hours with tech support and this is what they tell me. Hope it works
 
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