Specifications

3U Traffic Outstation Handbook
667/HB/26568/000 Page 116 Issue 15
9.6.3 Phone Line Sharing Facility (PLS)
9) 9.6.3 Ensure the unit has correctly determined whether the Phone Line
Sharing facility to a separate OMCU is required (‘
PLS:1’ if enabled
and ‘
PLS:0’ if disabled). If not, investigate the reason and correct.
Prior to PB681 issue 10, the ‘phone line sharing’ facility was always enabled and the
PLS handset command was not available. If the facility is not required, the ‘DM’ input
had to be connected to 0V as described in section 9.2.4 on page 105.
The ‘phone line sharing’ facility allows the MOVA unit to share the telephone line with
a separate Siemens OMCU as described in section 9.4 on page 108. The unit will
automatically attempt to determine whether the ‘phone line sharing’ facility is
required after complete initialisation, i.e. INI=3 or first time power-up, as follows:
If no LMU I/O boards are fitted then it implies that the OMCU application within this
PB681 unit is not going to be used, just the MOVA application. Therefore, the ‘phone
line sharing’ facility is enabled by default so it can be connected to a separate
OMCU.
If an LMU I/O board is fitted, then it implies that the OMCU application within this
PB681 unit is going to be used and not a separate OMCU unit. Therefore, the ‘phone
line sharing’ facility is disabled by default.
Regardless of what the unit decides, the ‘phone line sharing’ facility can be disabled
using the handset command “PLS=0” or enabled using the handset command
“PLS=1”.
When a local handset is connected to a unit running PB681 firmware, it will
normally display STCL OMCU+MOVA to identify that the firmware is capable
of providing both the OMCU and MOVA applications. However, if phone line sharing
to a separate OMCU is enabled, the unit will display SIEMENS MOVA to clearly
identify this as the MOVA unit, not the OMCU.
Tip!