User Manual

34 • I/O Modules
Special Modules
WAGO-I/O-SYSTEM 750
I/O Modules
2.1.1.8.1 Process Data Communication
During active process data communication, cyclic process data is exchanged
between master and slaves.
2.1.1.8.1.1 Configuration of the Control and Status Bytes
In process data communication, the control byte is configured as follows:
Table 12: Configuration of the control byte
Control byte
Bit
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
Value/
Description
0 0 Mailbox 0 0 0 0 0
Bit Value Description
2
0
0 Reserved (always 0)
2
1
0 Reserved (always 0)
2
2
0 Reserved (always 0)
2
3
0 Reserved (always 0)
2
4
0 Reserved (always 0)
0 Mailbox masked 2
5
1 Mailbox unmasked
2
6
0 Reserved (always 0)
2
7
0 During process data communication, always 0
(switch between process data communication and register communication)
In the status byte, messages, warnings and errors are signaled as follows:
Table 13: Configuration of the status byte
Status byte
Bit
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
Value/
Description
0
Gen-
eral
error
Mailbox 0
General.
warning
Mailbox
(remote)
Monitoring of
time behavior
0
Bit Value Description
2
0
0 Reserved (always 0)
0 No warning
2
1
1
Warning of obsolete process data. Indicates that no packet has been received
from the other party for a connection within the time defined as the error limit
(for times, see table from 2.1.1.7.2.3)