Siemens SINUMERIK 840D sl Equipment Manual page 73

4 active TCU connected in parallel to PCU
To operate a machine with more operating stations then the maximum number the
displacement mechanism ensures that only the permitted number of TCUs are active in
shadowing grouping. The remaining TCUs are switched to a passive mode, which means
they no longer represent a load relative to the resources. Thus the number of TCUs that can
be connected to one HMI application is practically no longer limited, the limitation is the
number of concurrently active TCUs.
Configuration
There are two new entries in the config.ini file for a TCU for the displacement mechanism:
• SUSPENDLOCK: controls whether the TCU can be displaced via the displacement
mechanism.
SUSPENDLOCK = 0 means that a displacement disable is not set (preset), i.e. the TCU may be
displaced by any other TCU.
SUSPENDLOCK=1 means that this TCU can never be displaced.
• SUSPENDPRIORITY: This entry specifies a priority for the displacement mechanism to the
TCU. In a displacement process the TCUs among the active TCUs with the lowest priority that
do not have a displacement disable will displaced. The priority is specified as numeric value
in the range 1 - 10.
The preset is 1 (lowest priority).
Note
If you set a displacement disable for a TCU then specification of a displacement priority is
unnecessary because it never is used due to the displacement disable.
Displacement rules
The TCU can assume the following states:
• The TCU is active and has user authorization: This can be identified as the TCU shows the
screen of the operating software and the screen is bright.
• The TCU is active, however, in the monitoring mode (i.e. it presently has no user
authorization): This can be identified as the TCU shows the screen of the operating software,
however, it is darkened in comparison to the TCU with user authorization.
• The TCU is passive: The TCU shows the selection menu of the possible connections instead
of a screen of the operating software, and the softkey for selection of the last active
connection of the TCU is shown in color.
When a TCU boots, the TCU always attempts to establish the first connection specified in
its config file. The TCUs from a shadowing group establish their specified connection one
after the other as long as the maximum number of permissible active operator units is not
exceeded.
If a TCU encounters the situation that this number is already reached in its power up, then
it attempts to obtain a connection via the displacement mechanism. If it can displace a
formerly active operator unit then it takes on the active status itself, otherwise it transitions
to passive status immediately after booting.
Handheld Terminal HT 8
Equipment Manual, 02/2024, A5E52918633B AA
General information and networking
4.3 Networking
73