User guide

Communication Capabiliites
98
890 USE 108 00 August 2001
Note: After the controller’s Modbus Plus node address is entered while in bridge
mode, then you will be attached to that controller.
If the address range in the Modbus message is between 70 ... 79, the controller
initiates an explicit attach address procedure which compares the Modbus address
to an address table stored in the controller, immediately following the configured
4xxxx real time clock. Up to 10 addresses in the range 70 ... 79 become pointers
to the table, which contains up to 10 stored routing paths for Modbus Plus. Each
routing path is five bytes in length. The routing path pointed to by each address is
applied to the corresponding message.
Explicit attach address routing implies that nonzero values may exist in any or all
routing addresses in the Modbus Plus message frame; it allows you to send
incoming Modbus messages through as many as four BP85 Bridge Plus devices
across as many as five Modbus Plus networks.
If the address range in the Modbus message is between 80 ... 255, the controller
initiates an implicit attach address procedure which divides the address by 10 and
uses the quotient and remainder as the first and second bytes, respectively, in a
routing path. Implicit attach address routing implies that there may be nonzero
values in routing addresses 1 and 2 in the Modbus Plus message frame; it allows
you to send incoming Modbus messages through one BP85 Bridge Plus device
across up to two Modbus Plus networks.