User Manual

Quatech QTM-8524 Manual 15
1.3.3 Operation Principle (Refer to Figure 1.3.2.1 & 1.3.2.2):
(1) The Host PC sends out a command via COM1.
(2) The QTM-8520 or upstream QTM-8524 converts the RS-232 signal into
a RS-485 signal or a RF signal respectively.
(3) All modules connected to the RS-485 network will simultaneously
receive this command. Each module in the network will extract the
destination address field and compare this value to its local module
address. The receiving wireless module first converts the RF signal to
RS-485, then sends the command to the downstream modules.
(4) The module to which the command was addressed will execute it, and
the other modules will ignore the command.
(5) After executing the command, the addressed module sends a response
back to the host PC over the RS-485 or RS-485/RF network.
(6) The QTM-8520 or upstream QTM-8524 module processes the response
and converts it from RF/RS-485 to RS-232 for use by the Host PC
(7) Host PC will interpret this result and take appropriate action.