Siemens SINUMERIK 840Di Function Manual page 1064

Detailed description
2.12 Block descriptions
The interface between the individual control units and the NCU (PLC) is the M : N interface
in data block DB19 (see FB 2 above, Chapter 5 Signal Description). FB 9 uses the signals of
these interfaces.
Apart from initialization, sign-of-life monitoring and error routines, the following basic
functions are also performed by the block for operating-unit switchover:
Tabulated overview of functions:
Basic function
MMC call waiting
MMC coming
MMC going
Forced break
Operating focus changeover to
server mode
Active/passive operating mode:
MCP switchover
Brief description of a few important functions
Active/passive operating mode
An online MMC can operate in two different modes:
Active mode:
Passive mode:
After switchover to an NCU, this initially requests active operating mode in the PLC of the
online NCU. If two MMCs are simultaneously connected online to one NCU, one of the two is
always in active and the other in passive operating mode. The operator can request active
mode on the passive MMC at the press of a button.
MCP switchover
As an option, an MCP assigned to the MMC can be switched over at the same time. To
achieve this, the MCP address must be entered in the mstt_adress parameter of the
NETNAMES.INI configuration file on the MMCs and MCPEnable must be set to true. The
MCP of the passive MMC is deactivated so that there is only ever one active MCP on an
NCU at one time.
Boot condition
To prevent the previously selected MCP being reactivated when the NCU is restarted, input
parameters
MCP1BusAdr = 255 (address of 1st MCP) and MCP1STOP =TRUE (deactivate 1st MCP)
must be set when FB1 is called in OB 100.
2-152
Meaning
MMC wants to go online to an NCU
MMC is connecting to an NCU
MMC is disconnecting from an NCU
MMC must break connection to an NCU
Change operating focus from one NCU to the other
Operator control and monitoring/monitoring only
As an option, MCP can be switched over with the MMC
Operator can control and monitor
Operator can monitor (MMC header only)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
Power Line Basic PLC Program (P3)