WAGO I/O-SYSTEM 750 Manual page 46

46 • I/O Modules
Special Modules
2.1.1.8.2.2 Setup
If bit 5 in the control byte is set, the mailbox is unmasked. It begins with byte
3 of the process image after the control/status byte and the internal byte. It
covers, depending on the set size, 6, 12 or 18 bytes of the process data (see
page 32, Figure 9). In this area, the data is interpreted as mailbox data, so that
commands (opcodes) can be sent here.
The setup of the data in the mailbox is always identical:
Set up
of the
mailbox
Figure 16: Setup of the mailbox
This basic form applies for query and response alike. The query is entered in
the output process image of the module, the response is extracted from the in-
put process image.
Note
The content of the mailbox is only interpreted by the module if the opcode is
changed or the toggle bit inverted. A change in the parameters does not lead
to any processing of mailbox content.
If bit 2
used bytes of the query are not utilized.
Byte 0 Control/status byte
Byte 1 Internal
byte
Byte 2 Opcode
Byte 3 Toggle
byte
Bytes 4...19 Parameters The interpretation of the parameters depends on the
5
of the control byte is set, there is a mailbox query (see Table 17). Un-
The opcode identifies the command and determines
the interpretation of the parameters.
Byte 3 contains the toggle bit (bit 7) and the return
value in the response.
opcode. The number of parameters is dependent on
opcode and mailbox size.
WAGO-I/O-SYSTEM 750
I/O Modules