Figure 59: Rtu Loopback/Maintenance Message Format - GE PACSystems RX7i Reference Manual

Message (08): Loopback/Maintenance (General)
Format:
Query:
▪
The Function code is equal to 8.
▪
The Diagnostic Code is two bytes in length. The high order byte of the Diagnostic Code is the first
byte sent in the Diagnostic Code field. The low order byte is the second byte sent. The
loopback/maintenance command is defined only for Diagnostic Codes equal to 0, 1, or 4. All other
Diagnostic Codes are reserved.
▪
The Data field is two bytes in length. The contents of the two Data bytes are defined by the value of
the Diagnostic Code.
GFK-2222AD
Func
Address
08
Func
Address
08
Normal Response

Figure 59: RTU Loopback/Maintenance Message Format

April 2018
Chapter 6. Serial I/O, SNP & RTU Protocols
Diagnostic
Error Check
Data
c Code
0, 1, or 4
DATA 1 DATA 1
Query
Diagnostic
Error Check
Data
c Code
0, 1, or 4
DATA 1 DATA 1
243