Rockwell Automation 900 Temperature Controller Communications Functions - Series B - Manual (Page 21)

Publication 900-UM004D-EN-E - July 2010
Bulletin 900 Communications Procedures 900-TCx (CompoWay/F) 2-5
Structure of Command Text PDU (Protocol Data Unit) Structure
An MRC (Main Request Code) and SRC (Sub-Request Code) followed by the
various required data is transferred to the command text.
Service request PDU
The MRES (Main Response Code) and SRES (Sub-Response Code) are
transferred to the response frame following the above MRC/SRC. Data is then
transferred following the MRES and SRES.
Service response PDU (during normal operation)
If the specified command text could not be executed, the service response
PDU will contain only MRC/SRC and MRES/SRES.
Service response PDU (command text not executed)
MRES/SRES provides the response code. MRES/SRES are not output when
processing ends in a normal operation.
Area Definitions
Areas comprise only the variable area.
MRC SRC Data
MRC SRC MRES SRES Data
MRC SRC MRES SRES