Rockwell Automation Publication 1756-PM020F-EN-P - January 2019 83
All Requests Start with these Fields: [CMD] [STS] [TNS] [FNC]
• [CMD] 1-byte, Request command code
• 0x0F in PLC-5 and SLC commands
• 0x0N in PLC2 commands (N is the hex value for the command)
• [STS] 1-byte, status code, 0x00 in commands
• [TNS] 16-bits, transaction identifier
• [FNC] 1 byte, function code (not included in some PLC2 commands)
All Replies Start with these Fields: [CMD] [STS] [TNS]+[EXT STS]
[CMD] 1-byte, Reply command code
• 0x4F in PLC-5 and SLC commands
• 0x4N in PLC2 commands (N is the same hex value in the corresponding Request CMD)
• [STS] 1-byte, status code
• 0x00 (success)
• 0xNN is error code (N is any hex value)
• 0xF0 means fourth field present (EXT STS] See following.
• [TNS] 16-bits, unique transaction identifier
• [EXT STS] 1-byte, extended status error code
• only present if [STS]=0xF0
See also
PCCC Commands on page 81
Use the PLC-2 commands to access one tag in a Logix 5000 controller. After
sending the command, it is acceptable to map the message to an INT(16 bit
integer) tag in the Logix 5000 controller. All the PLC2 commands access the
same tag, typically an INT array.
Logix Designer handles protected and unprotected commands the same way,
whether the access for the data is set to Read/Write, Read Only, or None.
See also
PCCC Commands on page 81
This command provides the read capability for the PLC-2 commands.
Request Format: [PLC-2 address] [size]
[PLC-2 address] 2-bytes; byte offset from start of file, on 16-bit boundary, low byte first
• [size] 1-byte; must be an even number of bytes
Reply Format: [data]
[data] is up to 244 bytes
See also
PLC-2 Communication Commands on page 83
Commands
Unprotected Read (CMD=01,
41; FNC not present)
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