How Does The Io Router Work - Siemens CP 1626 Operating Instructions Manual

4.4.3

How does the IO router work?

Requirements
A CP 1626 communications processor is required in a PC station. The communications
processor can be both IO controller and IO device at the same time.
Configuration
The communications processor is first configured as an IO controller. Its process controller
user program serves the IO devices assigned to it on the Industrial Ethernet bus.
The same communications processor is also configured as an IO device of an IO controller
for the control level. This IO device is assigned transfer submodules in the configuration that
represent the routed data.
Note
The program for this IO device in the PC station can be any IO device user program. It must
simply run through the full initialization phase according to the IO-Base user program.
When operating the CP 1626 as an IO router, with a given cycle time fewer IO devices are
possible than in the normal mode as a PROFINET IO controller. The number depends on the
configuration.
If 2 IO controllers want to access a certain output submodule or bit of an output submodule,
the following table shows which combinations are permitted.
Access to data
IO controller 1
Example:
When IO controller 1 writes to a certain area of an output submodule, IO controller 2 cannot
write to it at the same time; therefore: No.
You should avoid bit-by-bit assignment with transfer submodules.
In the configuration, input submodules can also be assigned bit-by-bit to multiple transfer
submodules.
This function should, however, not be used because input submodules can fundamentally be
read completely by two IO controllers at the same time.
Note
You do not need to worry about the transfer modules in your C user program because they
are managed by the system itself.
CP 1626
Operating Instructions, 11/2018, C79000-G8976-C434-03
Access to data
-
write
read
IO controller 2
write
No
Yes
Operating hardware
4.4 IO routing
read
Yes
Yes
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