Siemens SINUMERIK 840Di Function Manual page 1216

Detailed Description
2.5 Linking PLC CPUs to 840D
Interface MCP/PLC, interface HHU/PLC (Ethernet link)
MCP/PLC and HHU/PLC data exchange takes place via the integrated CP's Ethernet bus.
The CP transfers the MCP/HHU signals to and fetches them from the PLC's internal DPR
(Dual-Port RAM). On the PLC side, the basic program handles communication with the user
interface. The basic-program parameters (FB1, DB7) define the operand areas (e.g. I/O) and
the start addresses.
Interface MCP/PLC (PROFIBUS link)
MCP/PLC data exchange takes place via the PLC's PROFIBUS. The MCP's I/O addresses
must be set in the PLC's process image area and via HW configuration in STEP7. The
MCP*In, MCP*Out pointer variables must be set to the same addresses. The selected DP
slave number must be entered in MCP*BusAdr.
Interface MCP/PLC, interface HHU/PLC (MPI link)
MCP/PLC and HHU/PLC data exchange takes place via the PLC's MPI interface. The
Communication with global data (GD) service (= implicit global data communication) is used
for this purpose (see also STEP7 User Manual). The PLC operating system handles the
transfer of signals from and to the configured operand areas. The STEP7 NetPro configuring
tool is used to define both GD parameters and operand areas (e.g., I/O) and their start
addresses. The addresses assigned in NetPro must also be set in the MCP*In, MCP*Out
pointer variables on FB1.
Other parameters for MCP configuration must be set on FB1 in accordance with the FB1
description.
Please refer to chapter "Configuring the machine control panel, handheld unit" for more
detailed information about configuration.
2.5.4 Diagnostic buffer on PLC
General
The diagnostic buffer on the PLC, which can be read out using STEP7, contains diagnostic
information about the PLC operating system.
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PLC Basic Program Solution Line (P3 sl)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0