Standard Transmission Frame (In The Rs232/Rs485 Single Point Connection) - Edwards STP-iS2207 Series Instruction Manual

Table 20 shows ASCII characters being used in the transmission control, error control and handshake
in the application layer.
5
Transmission layer
Application layer
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
Transmission frame when a message is below 255 characters (n<=255):
"Stx" and "Etx" are used as a start and an end character of the transmission frame, respectively.
MT-89E-001-C
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STP-iS2207 Series Turbomolecular Pump
ASCII HEX
character code
Stx 02
Etx 03
Etb 17
Ack 06
Nak 15
@ 40
# 23
! 21
Table 20 - Transmission control characters
1 2 3
ASCII Stx 0 0
Function
Transmission block start character
Transmission frame end character
Transmission block end character
Acknowledgment response
Non-acknowledgment response
Network frame ID character
Acknowledgment response
Non-acknowledgment response
.
n
4 5 5+n
1 C C
1 n
5+n+1 5+n+2
Etx LRC