User Manual

tina03e1-b (2004-02) BPG400 v1.om 33
The example is based on the following output string:
Byte No 0 1 2 3 4 5 6 7 8
Value 7 5 0 0 242 48 20 10 69
The instrument or controller (receiver) interprets this string as follows:
Byte No Function Value Comment
0 Length of data
string
7 (Set value)
1 Page number 5 BPG400
2 Status 0
Emission = off
Pressure unit = mbar
3 Error 0
No error
4
5
Measurement
High byte
Low byte
242
48
Calculation of the pressure:
p = 10
((242 × 256 + 48) / 4000 - 12.5)
= 1000 mbar
6 Software version 20
Software version = 20 / 20 = 1.0
7 Sensor type 10 BPG400
8 Check sum 69
5 + 0 + 0 + 242 + 48 + 20 + 10 =
325
dec
 01 45
hex
High order byte is ignored ⇒
Check sum = 45
hex
 69
dec
For transmission of the commands to the gauge, a string (frame) of five bytes is
sent (without <CR>). Byte 1 to byte 3 form the data string.
Byte no Function Value Comment
0 Length of data string 3 (Set value)
1 Data
→ admissible input strings
2 Data
→ admissible input strings
3 Data
→ admissible input strings
4 Check sum
(from bytes No 1 … 3) 0 … 255
(low byte of sum)
1)
1)
High order bytes are ignored in the check sum.
For commands to the gauge, six defined strings are used:
Byte No
Command 01234
2)
Set the unit mbar in the display 3 16 62 0 78
Set the unit Torr in the display 3 16 62 1 79
Set the unit Pa in the display 3 16 62 2 80
Power-failure-safe storage of current unit 3 32 62 62 156
Switch degas on
(switches itself off after 3 minutes)
3 16 93 148 1
Switch degas off before 3 minutes 3 16 93 105 214
2)
Only low order byte of sum (high order byte is ignored).
Example
4.6.1.2 Input String (Receive)
Format of the input string
Admissible input strings