Siemens MOBY FC 56 Technical Description page 84

Entry/Exit Check of an MDS in an SLG Field
6.3 Entry/Exit Checking Mode 1 (MDS_IO_control 1)
If a command is issued to the filehandler, the user must ensure that an MDS is
present in the SLG transmission window. The command will be executed
immediately. If there is no MDS in the SLG transmission window, an appropriate
error message is output (timeout error). This procedure can be used in all cases in
which the user recognizes the presence of an MDS (e.g. by limit switches). Use of
the NEXT command is possible, but not mandatory. The user handles part of the
MDS control in his program.
Note
This mode must be set when several MDSs can be in the field (multitag > 1).
6.4 Entry/Exit Checking Mode 4 (MDS_IO_control 4)
In this mode of operation absolutely no checking of MDS entry/exit is carried out by
the filehandler. The MDS control must be handled entirely by the user.
If a command is issued to the filehandler, it will be stored until an MDS arrives in
the transmission window of the SLG. The filehandler then commences the
processing of the command. Use of the NEXT command is possible, but not
mandatory.
6-4
FC 56
J31069-D0155-U001-A0-7618