J1939 Receiving Messages; Transport Protocol For Large Messages - ICPDAS GW-7238D User Manual

4.2.5 J1939 Receiving Messages

Input data points are combined according to PGN and Target Address.
If the Target Address is configured as 255, all messages with a matching
PGN will be parsed using the data point, regardless of source address. If
the Target Address is not 255, received messages must match both the
PGN and source address in order to be handled by the input data point.

4.2.6 Transport Protocol for Large Messages

Transmission and Reception of Large Messages
Messages with buffer sizes of 8 bytes or less can be directly sent and
received on J1939. However, messages with buffer sizes greater than 8
bytes must be fragmented, transmitted, and reassembled using the J1939
transport protocol.
Users should reference the J1939-21 specification. It provides the
description of when and how the transport protocol is used by the GW-
7238D.
GW-7238D now provides a BAM (Broadcast Announce Message)
mechanism, when messages larger than 8 bytes in length and the
destination address is 255, the message will be sent or receive using
transport protocol BAM.
GW-7238D J1939 to MBTCP Server / MBRTU Slave Gateway User's Manual (Ver.1.0, Nov. 2011) --- 36