Edwards STP-iS2207 Series - Standard Transmission Frame (in the RS232;RS485 Single Point Connection)

STP-iS2207 Series Turbomolecular Pump
MT-89E-001-C
Page 78
5
SERIAL COMMUNICATION PROTOCOL
Table 20 shows ASCII characters being used in the transmission control, error control and handshake
in the application layer.
ASCII
character
HEX
code
Function
Transmission layer Stx 02 Transmission block start character
Etx 03 Transmission frame end character
Etb 17 Transmission block end character
Ack 06 Acknowledgment response
Nak 15 Non-acknowledgment response
@ 40 Network frame ID character
Application layer # 23 Acknowledgment response
! 21 Non-acknowledgment response
Table 20 - Transmission control characters
5.3.2 Standard transmission frame (in the RS232/RS485 single point connection)
The transmission frame has a single block or multiple transmission blocks. The transmission block
consists of a start control character, data block No. (3 digits), a message (up to 255 characters), an
end control character, and a checksum (LRC). The following table shows the transmission frame
where the message transmission character string is C
n
.
Transmission frame when a message is below 255 characters (n<=255):
1 2 3 4 5 5+n 5+n+1 5+n+2
ASCII Stx 0 0 1 C
1
C
n
Etx LRC
"Stx" and "Etx" are used as a start and an end character of the transmission frame, respectively.