
Chapter 4
CIP Over the Controller Serial Port
78
Rockwell Automation Publication 1756-PM020F-EN-P - January 2019
The following is an example of the fields for a CIP explicit message
connection using a Class 3 Transport encapsulated in PCCC sent
unfragmented, using DF1 Full Duplex on RS-232.
Name
Type
Description of Request Parameter
Semantics of Values
DLE
USINT
ASCII escape character
See the
DF1 Protocol and Command Set Reference
publication
STX
USINT
Start of message
DST
USINT
Address of destination
SRC
USINT
Address of source
CMD
USINT
Command = 0Ahex
STS
USINT
Status (0 in request)
See the
DF1 Protocol and Command Set Reference
publication
TNSW
UINT
Transaction sequence number
FNC
USINT
Fragmentation protocol function
Fragmentation Protocol
00hex (
Only
function)
Extra
USINT
Additional information for fragmentation protocol
Fragmentation Protocol
00hex (
Only
has no Extra)
CID
UINT
O-T Connection ID
Refer to the CIP Specification
Transport Header
UINT
Transport class 3 Sequence Count
Request Service
USINT
CIP Service Code
See
CIP Services
.
Request Path Size
USINT
Number of 16-bit words in the Request Path
Request Path
EPATH
Logical or Symbolic Segments, or both
Service Data
Service data
DLE
USINT
ASCII escape character
See the
DF1 Protocol and Command Set Reference
publication
ETX
USINT
End of message
BCC or CRC
USINT or UINT
Block Check Character
Cyclic Redundancy Check
See the
See also
CIP Service Request/Response Format
The fragmentation protocol allows messages up to 510 bytes to be sent over
PCCC/DF1, which has an inherent limit of 240 bytes. It allows each
fragment to be identified as it is transferred, with each fragment being
acknowledged (Ack or Nak) before the next fragment is sent, and provides
the ability for the client device to abort the fragmentation sequence if
necessary. This fragmentation protocol is used only with the 0A and 0B
PCCC commands.
Fragmentation Protocol