i got some problem in setting up the Modbus communication in my system.

if i poll 1-50 register then no error but if i poll more than 60 then i got the error.
polling 1-50 then 51-100 digital input is fine.

but polling 1-100 input the error occur.

any idea???

thanks,
jojit

 

Sounds like either your master or your slave doesn't want to return more than 50 registers at a time (probably the slave, because if the limitation was in the master, it probably wouldn't let you set up the larger transaction). This is not too uncommon.

 

What error did you get?

William (Bill) L. Mostia, Jr. PE
Fellow
SIS-TECH Solutions, LP
Any information is provided on Caveat Emptor basis.

 

Hello,

Try use the Modbus Tester from www.modbus.pl to check what errors you have.

Regards,
Andrzej