Chapter 8 Communication Functions
8-5
8.1.3 Frame Structure

1) Base Format

(1) Request frame(external communication device → MASTER-K120S main unit), (Max. 256 Bytes)
Header
(ENQ)
Station
number Command Command type Structurized data area Tail
(EOT)
Frame check
(BCC)
(2) ACK Response frame (MASTER-K120S main unit → external communication device, when receiving data normally)
(max. 256 Bytes)
Header
(ACK)
Station
number Command Command
type Structurized data area or null code Tail
(ETX)
Frame check
(BCC)
(3) NAK Response frame (MASTER-K120S main unit → external communication device,
when receiving data abnormally) (max. 256 Bytes)
Header
(NAK)
Station
number Command Command type Error code (ASCII 4 Byte) Tail
(ETX)
Frame check
(BCC)
Remark
1) Used control codes are as follows. Be familiar with the following control codes. Because they are importantly
used for communication.
Codes Hex value Name Contents
ENQ H05 Enquire Request frame initial code
ACK H06 Acknowledge ACK response frame initial code
NAK H15 Not Acknowledge NAK response frame initial code
EOT H04 End of Text Request frame ending ASCII code
ETX H03 End Text Response frame ending ASCII code