Chapter8 Communication Function
8-28
7) Reading PLC Status(RST)
(1) Introduction
This is a function that reads flag list including operating status of PLC and error information.
(2) PC request Format
Format name Header Station No. Command Command type
Tail Frame check
Frame (Example)
ENQ H0A R(r) ST EOT
BCC
ASCII value H05 H3041 H52(72) H5354 H04
Item Explanation
BCC
When command is lowercase(r), only one lower byte of the value resulted by adding 1 Byte
each to ASCII values from ENQ to EOT is converted into ASCII and added to BCC.
(3) Response Format(ACK response)
Format name Header Station No. Command
Command
type
PLC status data
(Hex 20 Byte)
Tail
Frame
check
Frame (Example)
ACK H0A R(r) ST Status data Format ETX
BCC
ASCII value H06 H3041 H52(72) H5354 [
ఐ
] H03
Item Explanation
BCC
When command is lowercase(r), only one lower byte of the value resulted by adding 1 Byte
each to ASCII values from ACK to ETX is converted into ASCII and added to BCC, and sent.
(4) Response Format( NAK response)
Format name Header Station No. Command Command type
Error code
(Hex 2 Byte)
Tail Frame check
Frame (Example)
NAK H0A R(r) ST H1132 ETX BCC
ASCII value 15 3041 5272 5354 31313332 03
Item Explanation
BCC
When command is one of lower case(r), only one lower byte of the value resulted by adding
1 Byte each to ASCII values from NAK to ETX is converted into ASCII and added to BCC,
and sent.
Error code
Hex and 2 bytes(ASCII code, 4 bytes) indicate error type. For the details, see 8.1.8 Error
codes.