Process Image; Overview - WAGO -I/O-SYSTEM 750 Series Manual

2.1.1.7

Process image

2.1.1.7.1

Overview

The length of the process image of the AS-Interface master module can be set
to fixed sizes of 12, 20, 24, 32, 40 or 48 bytes.
It consists of a control or status byte, a mailbox with a size of 0, 6, 10, 12 or
18 bytes and the AS-Interface process data, which can range from 0 to 32
bytes (Mode 1).
Alternatively, the mailbox can be set up to overlap, i.e. the mailbox is
temporarily superimposed on the AS-Interface process data with a length of 6,
10, 12 or 18 bytes depending on the total length of the process image that has
been configured (Mode 2).
Register communication is used to set up the module via the parameter
channel (Mode 3).
configured mailbox
Changing between Mode 1 (permanently configured mailbox) and Mode 2
(overlapping mailbox) as well as the setting up of the mailbox and process
image sizes is carried out with the WAGO-I/O-CHECK 2 commissioning
tool or by means of the parameter channel via address 0. The values set are
mirrored in Register 33.
Mode 3 (register communication) is switched on and off with bit 2
control byte. As this mode has a superimposed function, the previously
activated Mode 1 or 2 remains active after switching off.
All possible settings relating to the total process image length and mailbox
length are listed in the following tables.
WAGO-I/O-SYSTEM 750
I/O Modules
Mode 1
permanently overlapping mailbox
(normal mode)
Control/Status Control/Status
(1 byte, byte 0) (1 byte, byte 0)
Internal use
(1 byte, byte 1) (1 byte, byte 1)
Mailbox
(acyclical data, (acyclical data,
0-18 bytes long, 6-18 bytes long,
bytes 2 to n)
Process data (cyclical data,
(cyclical data, 0-32 bytes long,
0-32 bytes long, bytes n+1 to m)
bytes n+1 to m) (take validity of data
into account!)
750-655 [AS-Interface master module]
Mode 2.1 Mode 2.2
overlapping mailbox
activated deactivated
Control/Status
(1 byte, byte 0)
Internal use Internal use
(1 byte, byte 1)
Mailbox
bytes 2 to n)
Process data
(cyclical data,
Process data
0-32 bytes long,
bytes 2 to m)
• 21
Process image
Mode 3
register
communication
Control/Status
(1 byte, byte 0)
Internal use
(1 byte, byte 1)
Register data
(2 bytes, bytes 2 to
3)
Invalid data
(bytes 4 to m)
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of the