Wenglor CP08MHT80, Operating Instructions Manual

Page: 14 / 19

Adjustment 14
Protocol for Communications via the RS-232 Interface
Frame Layout for Data Transmission
Transmitting Partner Characters (ASCII) Receiving Partner Frame Segment
Start character / (ASCII 47) => Connect Frame header
Length information 2 Byte => Connect Frame header
Command bytes 2 Byte => Frame header
1 st data byte 2 Byte => Data information User data
2 nd data byte 2 Byte => User data
.. .. => Data information User data
n th Data byte .. => Data information User data
Checksum (BCC) 2 Byte => Frame end
Stop bit . (ASCII 46) => Disconnected Frame end
Calculating the Checksum BCC (Block Check Character)
The Checksum is generated from an EXOR frame operation.
Start Character Length Command Data Checksum Stop character
/ 02 0D 00 59 .
2FH 30H 32H 30H 44H 30H 30H 35H 39H 2EH
Data used to calculate the checksum
Calculating Example: Program Example:
/ 2FH = 0010 1111
0 30H = 0011 0000
XOR = 0001 1111
2 32H = 0011 0010
XOR = 0010 1101
0 30H = 0011 0000
XOR = 0001 1101
D 44H = 0100 0100
XOR = 0101 1001
0 30H = 0011 0000
XOR = 0110 1001
0 30H = 0011 0000
XOR = 0101 1001 => Checksum = 59H
Start
Transmitting Frame = “/020D0059.” (Example)
Transmitting Frame Length=10 (in this example);
checksum = 0; n = 1;
as long as: n < (Transmitting Frame Lenght - 3)
Checksum = Checksum EXOR Transmitting
Frame charakter (n)
n = n +1
End