Communication Protocols
Copyright IXXAT Automation GmbH
88
IEM Manual, 1.5
Note:
If a submodule is designed to be bi-directional, two process varia-
bles have to be created and mapped in the input respective output
IO area of the SHM. In that case the host application is responsible
to keep both data sets consistent.
There is a small set of local, built-
in objects located on the IEM, which don’t
have to be created. Those are
DeviceName
and
IP_Parameters
. These varia-
bles don’t possess any address reference and can only be read by the Host
using the
COM_k_GET_VALUE
service and the
w_devPropAccess
field of the
protocol specific address (see also
COM_k_PNIO_DEVICE_XXX
macro in
COMpnio.h).
Built-in object
Description
COM_k_PNIO_DEVICE_NAME
Device name (temporary)
COM_k_PNIO_DEVICE_NAME_REM
Device name (remanent)
COM_k_PNIO_DEVICE_IP_SETTINGS
IP Settings (temporary)
COM_k_PNIO_DEVICE_IP_SETTINGS_REM IP Settings (remanent)
Write access on them is allowed only from the network. If one of these objects
has been changed by the PROFINET Controller/Supervisor, the Host receives
the
COM_k_EVT_VARIABLE_ACCESS
event with a corresponding parameter
(value from the
COM_k_PNIO_DEVICE_XXX
set).
5.1.4 Process data mapping
In PROFINET all process data have to be placed in the input respectively out-
put IO area of the SHM. Since every submodule is accessed exclusively by the
PROFINET stack of the IEM, no copying process of the whole IO image at
once takes place in the IEM. So, gaps between variables are generally al-
lowed. The only and very important
requirements to the mapping of the
process data is reserving a place behind of every process variable
for IO
Provider Status (IOPS) (1 byte) and IO Consumer Status (IOCS) (1 byte) (see
Figure 5-3).
Slot: 1
Subslot: 3
Size: 10bytes
Offset: 0
IOPS
1 byte
IOCS
1 byte
Slot: 1
Subslot: 4
Size: 6 bytes
Offset: 12
IOPS
1 byte
IOCS
1 byte
Slot: 2
Subslot: 2
Size: 54bytes
Offset: 20
IOPS
1 byte
IOCS
1 byte
Slot: 1
Subslot: 1
Size: 4 bytes
Offset: 0
IOPS
1 byte
IOCS
1 byte
Slot: 1
Subslot: 2
Size: 10bytes
Offset: 6
IOPS
1 byte
IOCS
1 byte
Slot: 2
Subslot: 1
Size: 46bytes
Offset: 18
IOPS
1 byte
IOCS
1 byte
Inputs
Outputs
Figure 5-3: Placement of process data in the IO area of the SHM