hi,
In my application i have to communicate with 3 microcontrollers(pic18f4520) using modbus and labview will be master
I am using ni modbus library
I have to read holding register , write single register and read coils with all the 3 slaves
It works fine until any of the byte in the modbus response frame becomes FF
Here for example i am trying to read holding register(address 0x220) from slave(address 2) (see the attachement : count 11)
02 03 02 20 00 01 84 4b --- Master query to microcontroller
02 03 02 03 e4 fc ff -- Micro controller response to master(labview)
As you can see valid response is comming from the microcontroller
Still labview is showing an error "Time out expired before operation completed"
When we press OK it again come to first microcontroller and start sending from first query and stops at this count 11
This happens only when any of the byte become FF, even when any of the data bytes becomes FF it behaves like thisway
Labview is getting the correct response but its not proceeding with next query
If the byte becomes other than FF the communication resumes
Thanks in advance
