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Chapter 7
7.5.7
MASTER-K
Dedicated communication
Read the status of PLC (RST)
1) Introduction
This command is used for reading the status of PLC such as operation status, error
information, etc.
2) Request format (External device ! PLC)
Format
name
Header
Station number
Main
instruction
Instruction
type
Tail
Frame check
Frame
example
ENQ
h01
R (r)
ST
EOT
BCC
ASCII
value
h05
h3031
h52 (72)
h5354
h04
BCC : When the main instruction is small character (r), the lower byte of summation from
ENQ to EOT is converted into ASCII format and added to frame as BCC check.
3) Response format (PLC ! External device : ACK response)
Format
name
Header
Station number
Main
instruction
Instruction
type
Status data
Tail
Frame
check
Frame
example
ACK
h01
R (r)
ST
(Hex 20 bytes)
ETX
BCC
ASCII
value
h06
h3031
h52 (72)
h5354
(ASCII code 40 bytes)
h03
Station number, main instruction, and instruction type is same as those of the request
format.
When the main instruction is small character (r), the lower byte of summation from
ACK to ETX is converted into ASCII format and added to frame as BCC check.
Status data : The status data is consist of 20 byte of hexadecimal numbers. When the
PLC returns, it is converted to the ASCII code, and its size is doubled (40 bytes). See
the next page for detail of status data configuration.
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