Transmission Interface - Advantech SSPBMg–C200–BRE Installation And Operating Manual

12.3.1 T
RANSMISSION
A request packet (see TABLE
16
TABLE ) by the SSPB. The IDU is the bus master. The SSPB is only allowed to respond if
the first byte of the request packet matches its address and the checksum is consistent.
Upon reception of a request packet the SSPB will perform the following consistency checks:
1) Verify that the checksum is consistent.
2) Verify that the packet address corresponds with the SSPB address.
3) Verify that the received command corresponds to a defined command.
4) Verify that, if data is required for the command, its value is valid.
If the received packet passes test (1) and test (2) but fails in test (3) or in test (4), a response
packet will be returned. Bit #2 of byte #5 will be set to 1 to indicate that an inconsistency was
detected in the request packet.
I
NTERFACE
15
) is sent by the IDU and the respective response packet (see
SSPBMg-C200-BRE
Page 43