WAGO -I/O-SYSTEM 750 Manual page 81

WAGO-I/O-SYSTEM 750
750-882 Media Redundancy ETHERNET Controller
Hardware changes can result in changes of the process image!
If the hardware configuration is changed by adding, changing, removing or
reparametrisation of I/O modules with a data width > 0 bit, this result in a new
process image structure. The process data addresses would then change. If
adding I/O modules, the process data of all previous I/O modules has to be taken
into account.
A memory range of 256 words (word 0...255) is initially available in the controller
for the process image of the physical input and output data.
For the image of the MODBUS/PFC variables, the memory range of words
256...511 is reserved; meaning the image for the MODBUS/PFC variables is
created behind the process image for the I/O module data.
If the quantity of module data is greater than 256 words, all the physical input and
output data above this value is added to the end of the current process image in
a memory range; i.e., attached behind the MODBUS/PFC variables (word
512...1275).
The EtherNet/IP PFC variables are then mapped behind the remaining physical
I/O module data.This memory range includes words 1276 ... 1531.
The subsequent range, starting from word 1532, is reserved for future protocol
expansion and other PFC variables.
Access by the PLC to process data is made independently from the fieldbus
system in all WAGO fieldbus controllers; access is always conducted through an
application-related IEC-61131-3 program.
How the data is accessed from the fieldbus side depends on the fieldbus
however.
For the fieldbus controller, a MODBUS/TCP master can access the data via
implemented MODBUS functions, whereby decimal or hexadecimal MODBUS
addresses are used.
Optionally, data can also be accessed via EtherNet/IP using an object model.
Additional Information:
For a detailed description of these fieldbus-specific data access methods, refer to
the section "MODBUS Functions" or the section "EtherNet/IP (Ethernet/Industrial
Protocol)".
Function Description
Manual
81
1.5.0