LSIS Master-K K1000S - Page 173

Chapter 13 RS-232C function of K200S MASTER-K
13-27
4) Response format (PLC à External device : NAK response)
Format
name
Header Station number
Main
instruction
Instruction
type
Error code Tail
Frame
check
Frame
example
NAK h01 R (r) ST h1132 ETX BCC
ASCII
value
h15 h3031 h52 (72) h5354 h31313332 h03
① Station number, main instruction, and instruction type is same as those of the request
format.
② When the main instruction is small character (r), the lower byte of summation from
NAK to ETX is converted into ASCII format and added to frame as BCC check.
③ The error code is expressed as 2 byte of hexadecimal format ( 4bytes of ASCII
codes) and indicates the type of error. Please refer the error code table for details.
5) Example
Read the CPU status of station number 1. (No BCC check)
① Request format (Ext ernal device à PLC)
Format
name
Header Station number
Main
instruction
Instruction
type
Tail
Frame
example
ENQ h01 R ST EOT
ASCII
value
h05 h3031 h52 h5354 h04
② Response format (PLC à External device : ACK response)
Format
name
Header Station number
Main
instruction
Instruction
type
Status data
Tail
Frame
example
ACK h01 R ST (Hex 20 bytes) ETX
ASCII
value
h06 h3031 h52 h5354 (ASCII code 40 bytes) h03
③ Response format (PLC à External device : NAK response)
Format
name
Header Station number
Main
instruction
Instruction
type
Error code Tail
Frame
example
NAK h01 R ST h1132 ETX
ASCII
value
h15 h3031 h52 h5354 h31313332 h03