Offlink Addressing

Offlink addressing allows communication with a station (PLC) that is not on the local link and is required for PLCs that cannot have support and Ethernet interface (like SLCs). This is done via 1785-KA, 1785-KA5 or PI routing. The 1785-KA is a communications adaptor card for providing exchange between DH and DH+. The format for offlink addressing is:

PMM:C[options],u

Where:

• P = the router module pushwheel number (0 to 4) or board number.

• MM = the module type (RM, KA or KT)

• C = the channel number (0, 2 or 3)

• [options] is one or more of the following:

  • /B:b where b is the bridge address (1 to 376 octal).

  • /L:l where l is the link id (0 to 65535 decimal)

  • /G:g where g is the gateway to the final DH-485 link (1 to 376 octal)

  • /KA When communicating through a 1785-KA from DH+ to DH

• u = the station number of the remote PLC in octal. Station numbers are between 0 and 77 (octal) for DH+ channels, and between 1 and 376 (octal) for DH channels.

Consider the following diagram and examples:

In the picture above station addresses are noted (in parentheses) next to each unit. Each unit is addressed as follows:

Be aware that the SLCs may be addressed in either Single Hop (link is set to 0) or Gateway (where the incoming DH+ link ID is used) modes.

For detailed information on off-link addressing refer to the Allen Bradley Interchange Software Reference Manual.