Rockwell Automation 1747-KE,D17476.12 DH-485/RS-232C Interface Module - Manual (Page 27)

1 Publication 1747-UM005B-EN-P - March 2006
Chapter
3
Communicate with the Interface Module
This chapter explains:
• full- and half-duplex DF1 communication.
• local and remote half-duplex operation.
• communicating with master and slave DH-485 devices.
• communicating with a modem.
DF1 Communication The module supports full-duplex DF1 protocol and half-duplex DF1
slave protocol on its RS-232 connection to the host computer (using
the DF1 Port). The details of these protocols can be found in the DF1
Protocol and Command Set Reference Manual, publication
1770-RM516.
Full-duplex DF1 Protocol
Full-duplex DF1 protocol is provided for applications where high
performance peer-to-peer communication is needed.
In full-duplex mode, the module can send embedded responses. If the
embedded response detect option is set to auto-detect embedded
response, the module will not send embedded responses until it
receives one from the host. The module makes an assumption that if a
host computer sends embedded responses, it can also receive them.
In full-duplex mode, the destination address in a packet sent from the
host computer to the module is the address of the DH-485 node for
which the packet is intended. The source address in packets received
by the host computer from the module is the node address of the
sender.