Owner manual

4
tira90e1 (2014-01) RS232C.cp
1 Interface Protocol
The complete send string (frame) is nine bytes (byte 0 … 8) long. Bytes 1 … 7 form
the data string.
Byte No. Function Value Comment
0 Data string length 7 Constant value
1 Page No. 4 Constant value for CDGsci
1)
2 Status
→ "Status byte"
3 Error
→ "Error byte"
4 Measured value high byte <value>
→ "Calculation of pressure value"
5 Measured value mid byte <value>
→ "Calculation of pressure value"
6 Read command <value> Read value
7 Measured value low byte
1)
<value>
→ "Calculation of pressure value"
8 Checksum
→ "Synchronization"
1)
The "Sensor Type" that is accessible via Byte 7 in all other CDGs can now be deduced
from address 56 (Exponent) and 57 (Mantissa).
Bit 0 Definition
0 Continuous output of measured value
1 Individual measured value (polling)
1)
1)
→  8, "DataTxMode". Send a read command of any parameter to the gauge for
requesting a send string.
Bit 2 Bit 1 Definition
1 0 Manual setpoint setting
1 1 Zero adjust active
Bit 3 Definition
0 ⇔ 1
Toggle bit, changes with every string
received correctly
Bit 5 Bit 4 Definition
0 0 Current pressure unit mbar
0 1 Current pressure unit Torr
1 0 Current pressure unit Pa
Bit 6 Definition
0 Standard measurement mode
1 Reserved for internal use
Bit 7 Definition
0 Heating
1 Sensor temperature attained
1.1 Send String
Structure of send string
Status byte
(byte No. 2)