Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 141 of 265
15.3.16 Local Link Inhibit (LL)
An ‘LL’ control bit may be programmed to override the local link to an adjacent
controller. Normally other control bits from the computer would then operate the link.
15.3.17 Local Link Inhibit Confirm (LC)
An ‘LC’ reply bit may be returned to indicate that the Local Link is inhibited.
15.3.18 Fall Back Mode (FM)
An ‘FM’ control bit normally causes the controller to disable CLF mode whilst the
‘FM’ bit is active. Thus if UTC mode is not active, it prevents the controller running
CLF mode as the ‘fall back’ mode, forcing it to run a lower priority mode such as VA
or FT (assuming a higher priority mode is not active).
15.3.19 Fall Back Confirm (FC)
An ‘FC’ reply bit may be returned to indicate that an ‘FM’ control bit has been
received and actioned.
15.3.20 RTC Set to Stored Value (TS)
A ‘TS’ control bit may be programmed to cause the time in the Real Time Clock to
be set to the value stored in the configuration.
The ‘Time Sync’ signal is transmitted four times at 0101 levels, each level of 1-
second duration, with the clock being set at the start of the second ‘1’.
The signal can set either:
This will allow synching either:
a) minutes and seconds once an hour
b) hours, minutes and seconds once a day
c) day, hours, minutes and seconds once a week
This ‘TS’ time sync input bit can be configured without needing to configure UTC
mode so that it can be used by a local link.
15.3.21 RTC Synchronisation to Stored Value Confirm (CC)
A ‘CC’ reply bit may be returned to indicate Real Time Clock load signal (TS) has
been received and actioned. The signal is maintained for a pre-set period,
configurable in 1-second steps, but is normally set to 3 seconds.
15.3.22 RTC at Configured Time (RT)
A ‘RT’ reply bit may be returned at a specified time configured within the controller.
When this time is reached the reply bit is activated for a pre-set period, configurable
in 1-second steps, but normally set to 3 seconds.