Rockwell Automation 1770-KF3 DH-485 Communication Interface User Manual - Manual (Page 36)

Communicating with the KF3
Chapter 4
4Ć3
HalfĆDuplex DF1 Protocol Ċ Remote Mode
The valid range of slave addresses on a half-duplex network is 000-376
octal – a total of 255 stations. The valid range of addresses on a DH-485
network is 00-31 decimal. In order to make these two systems compatible,
two special submenu configuration options have been included in the KF3
(see Table 3.C).
The first, submenu option 6, must be set to the address of the half-duplex
master. This value is limited by the KF3 to a range of 00 to 77 octal (out
of a possible range of 000-376 octal). The default address is 10 octal.
The second configuration option, submenu option 7, must be set to the
group number. Group numbers range form 00 to 07, with each group
consisting of up to 32 DH-485 nodes. The KF3 uses group numbers to
create unique half-duplex DF1 addresses for each node on the DH-485
network.
In remote mode, the KF3 appears transparent to the half-duplex master, so
that remote SLC 500s can be polled directly as individual slaves on the
half-duplex network. The KF3 responds to the half-duplex master if the
station address specified corresponds to the node address of any master
(token-passing) station on the DH-485 network.
Messages from remote nodes on the DH-485 network (such as the SLC
500s) use the destination address of the KF3. To maintain its transparency
to the half-duplex master, the KF3 overwrites this destination address with
the value configured in submenu option 6. The message received by
the half-duplex master will contain a source address equal to the station
address specified in the poll packet and a destination address equal to the
address of the half-duplex master device.
Table 4.A provides the address conversion using the group number.
Remember that half-duplex DF1 (group) addresses are in octal and
DH-485 node addresses are in decimal.