How to Download data from a Datalogger's memory having RS 485 port & Modbus RTU protocol

[Kaku]

to download the data i have to send the request 010900000000B6 response of this command will be 01090A0B031B1114Z30AA015C294 But when i send this command through Serial Port, I am getting same string as command. Please suggest me the solution for this.

[LV_Pro]

Do a search on this site for MODBUS, it may help explain. MODBUS is a specific protocol, and I'm not sure that just sending the string you refer to is sufficient. Also, make sure that you have the communications cables correctly connected, it sounds like you may be getting just an echo back, that the output serial pin may be connected to the input side.