48 •
750-671 [Steppercontroller]
Process
Image
WAGO-I/O-SYSTEM
750
I/O
Modules
2.1.2.7 Process
Image
The 750-671 I/O module provides the fieldbus coupler/controller 12 bytes
input and output process image via 1 logical channel. The data to be sent and
received are stored in up to 7 output bytes (D0 … D6) and 7 input bytes (D0
… D6), depending on the operating mode. Output byte D1 and input byte D1
are reserved and have no function assigned. 1 I/O module control and status
byte (C0, S0) and 3 application control and status bytes (C1 ... C3, S1 ... S3)
provide the control of the data flow.
Please note
Mapping the process data of some I/O modules or their variations into the
process image is specific for the fieldbus coupler/controller used. You will
find both this information and the specific configuration of the relevant
control/status bytes in the section on "Fieldbus Specific Configuration of
Process Data" which describes the process image of the particular
coupler/controller.
2.1.2.7.1
Overview
A basic distinction is drawn between the cyclic process image and the mailbox
process image.
Cyclic process image
(Mailbox deactivated)
Mailbox process image
(Mailbox activated)
Off-
set
Input Data
Output Data
Output Data
Input Data
0
Status byte S0
Control byte C0
Status byte S0
Control byte C0
1 Reserved Reserved Reserved Reserved
2
3
4
5
6
7
Mailbox
MB0 ... MB5
Mailbox
MB0 ... MB5
8
Process data
D0 ... D6
Process data
D0 ... D6
Reserved Reserved
9
Status byte S3
Control byte C3
Status byte S3
Control byte C3
10
Status byte S2
Control byte C2
Status byte S2
Control byte C2
11
Status byte S1
Control byte C1
Status byte S1
Control byte C1
Switching between the two process images is conducted through bit 5 in the
control byte (C0 (C0.5). Activation of the mailbox is acknowledged by bit 5 of
the status byte S0 (S0.5).
