Owner manual

6
tira90e1 (2014-01) RS232C.cp
All variables in a receipt string that are addressed for reading are output on this
byte. For variable types >1 byte, each byte (e.g. low, high, or further bytes) has to
be addressed and read individually.
Read Command L-Byte → Read Data L-Byte
Read Command H-Byte → Read Data H-Byte
• After a write operation, the value of the addressed variable is output.
• After a reset (Power on) the software version is output on byte 6.
The recipient (master) is synchronized by checking three bytes:
Byte No. Function Value Comment
0 Data string length 7 Constant value
1 Page No. 4 Constant value for CDGsci
8 Checksum of bytes
No. 1 … 7
0 … 255 Low byte of checksum
1)
1)
Possible high bytes are ignored
The example is based on the following output string:
Byte No. 0 1 2 3 4 5 6 7 8
Value 7 2 16 0 125 0 20 0 69
The instrument or controller (receiver) interprets this string as follows:
Byte No. Function Value Comment
0 Length of
datastring
7 (Set value)
1 Page No. 2 CDGsci with output signal 10.00 V
2 Status 16 Pressure unit = Torr
3 Error 0 No Error
4
5
Measurement
High byte
Mid byte
125
0
Calculation of pressure value: Conversion
formula →  5
6 Read command 20 Software version = 20 / 20 = 1.0
7 Measurement
Low byte
0 Calculation of pressure value: Conversion
formula →  5
8 Check sum 169 2 + 16 + 0 + 125 + 0 + 20 + 6 =
169
dec
≙ 00 A9
hex
High order byte is ignored 
Check sum = A9
hex
≙ 169
dec
Read command
(byte No. 6)
Checksum and synchronization
(byte No. 8)
Example