Function description
Operating Manual PSSu E S 2AI I se(-T)
21417-EN-04
22
Bit sequence in the PII, status byte only, no input data:
Input
PII
Assignment
Input I0
1
LSB status byte
...
...
8
MSB status byte
Input I1
9
LSB status byte
...
...
16
MSB status byte
4.3.6.2
Status byte
ST modules for analogue input can transfer a variety of status information to the ST-PII
(see table below for the conveyed status). The information is transmitted using the input's
status byte. Read access (R) is configured for the input for that purpose.
Structure and contents of the status byte:
Bit number Content Meaning
0
0
Input value above the lower limit value
1
Value below the lower limit value
1
0
Input value below the upper limit value
1
Value exceeds the upper limit value
2 / 3
0 0
Limit value 1 inactive
0 1
Input value greater than or equal to limit value 1
1 0
Input value less than limit value 1
1 1
Reserved
4 / 5
0 0
Limit value 2 inactive
0 1
Input value greater than limit value 2
1 0
Input value less than or equal to limit value 2
1 1
Reserved
6
0
Valid data from A/D converter
1
No valid data from A/D converter
7
0
Reserved
1
Reserved
