User's Manual

455U-D Radio Modem Module User Manual
Page 48 © Jan 2008
To use OPR, select “Use Host Protocol” in
the “Operating Mode” section of the
configuration screen. Select the host
protocol type in the drop-down box below.
(Modbus ASCII or RTU, DF1 or DNP3).
Path Configuration
When “Use Host Protocol” is selected, you
can click the “Paths” button to access the
routing paths configuration. Routing paths allow you to enter the path through the network to
use when the matching host protocol address is detected as the destination address in the host
protocol frame. The following example will send messages to protocol address 1 to the
modem with address 11, via modem 10 as a store and forward. Messages to address 12 are
sent to modem address 12, using modems 10 and 11 as store and forward. Messages to
protocol address 13 are sent directly to the modem with address 13.
Configuring for Modbus Protocol (RTU or ASCII)
With Modbus protocol, the master station does not have an address. This means that for each
remote, you need to configure a path back to the master station which uses the remote’s own
address as the Protocol address.
At the master station, you must configure a path to each remote station, using the address of
the remote station as the protocol address.
Modbus RTU Protocol
When configured for Modbus RTU Protcol, the modem ignores the configured Rx Timeout
value, and sets it to the correct value for the modbus RTU protocol.
Modbus ASCII protocol
The correct value for serial timeout in the Modbus ASCII protocol is 1 second, hower, this is
normally too long. Setting the serial timeout value to 0 causes the actual serial timeout to be 1
second. Otherwise, the configured value is used. Unless your application requires the 1 second
serial timeout, select PLC mode to set a good value for serial timeout.
DF1 protocol
The 455U works with DF1 Half Duplex protocol. Some DF1 Half Duplex frames are only sent
from a slave to a master. These frames do not include a destination address. For DF1 protocol
to work, the DF1 Half-Duplex master must be configured with address 0. (This is normally the
case).