Chapter 6. Serial I/O, SNP & RTU Protocols
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Message (17): Report Device Type
Format:
Figure 62: RTU Report Device Type Message Format
Query:
The Report Device Type query is sent by the master to a slave in order to learn what type of
programmable control or another computer it is.
â–ª An Address of zero is not allowed as this cannot be a broadcast request.
â–ª The Function code is 17.
Response:
â–ª The Byte Count field is one byte in length and is equal to 5.
â–ª The Device Type field is one byte in length and is equal to 43 (hexadecimal) for PACSystems
â–ª The Slave Run Light field is one byte in length. The Slave Run Light byte is equal to OFFH if the CPU is
in RUN Mode. It is equal to 0 if the CPU is not in RUN Mode.
â–ª The Data field contains three bytes. For PACSystems CPUs, the first byte is the Minor Type, and the
remaining bytes are zeroes. The following table lists minor types.