That's bollocks in itself, possibly a requirement of a particular protocol but nothing to do with the MAX chips or RS-485.
ok, if this is like you say, my test is in vain because my goal on this test is avoid that.
Then I don´t have idea for what is my problem with the respons of device.
What libraries? Are we talking Modbus or just generic comms libraries?
I´m talking about the Modbus libraries like:
SimpleModbusMaster.h ---> https://code.google.com/p/simple-modbus/
MasterModbus.h -----------> https://github.com/2-718/ModbusMaster
And i think start try with RS485_protocol.h -------->http://www.gammon.com.au/forum/?id=11428
but i´m not sure that this library generates CRC code.
Do you have to use Modbus, or was that just the last thing you tried?
I need use Modbus RTU, for be more specific, i my device is the PM1200
Note: I don´t know if can publish marks, but I prefer avoid it for invalid my post
thanks for you attention Graynomad.