Structure Of Command Text; Pdu (Protocol Data Unit) Structure; Variable Areas And Parameter Areas - Omron KM50 Communications Manual

2. 2 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 are sent as the command text.
• Service Request PDU
MRC SRC
The MRES (Main Response Code) and SRES (Sub-Response Code) are sent in the
response frame following the above MRC/SRC.
• Service Response PDU (Normal Response)
MRC SRC MRES SRES
If the specified command text could not be executed, the service response PDU will
contain only the MRC/SRC and MRES/SRES.

■ Variable Areas and Parameter Areas

The KM50-C/-E use two areas for data communications. The variable area is accessed to read
measurement values.
The variable area is separated into areas for the three types of measurement values,
instantaneous, maximum, and minimum, and an area to read the measurement log. The
addresses of the variables and measurement values are specified to read the measurement
values and measurement log.
The parameter area is used to read and write the current parameter settings. The address of the
parameter to read or write is specified to monitor or change the set value.
Tables of the variable area and parameter area are provided in Section 3 CompoWay/F
Communications Data.
Other commands do not use the variable and parameter areas.
Data
Data

2. 2 Structure of Command Text

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