Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 195 of 265
26.3 Switch Function Setting
The event timetable is introduced by a master time clock timetable setting with a
function number of ‘2’. Following the function number 2 in the MTCS timetable will
be a ‘Parameter’ number. This parameter number refers to a combination of event
switches that are required to be inoperative ‘0’ or operative ‘1’. Thus, when the
MTCS invokes a time switch parameter, a combination of events may be set
operative or inoperative.
Individual time switch events can also be set and cleared directly, without using the
parameter array. A function number of ‘3’ sets an event and a function number of ‘4’
clears an event.
The use of time switch parameters and function ‘2’ to select a combination of event
switches has been retained to allow easier upgrade of existing configurations. Their
use on new configurations is not recommended. Instead, use the timetable functions
‘3’ and ‘4’ to set/clear the individual time switch events.
In the event of a time clock failure, all the timetable settings are set to their default
state (see section 26.4).
32 event switches are available to be defined (0-31); each one may be defined as
any one of the following event types:
26.3.1 Switch an Input/Output Active/Inactive/Normal
An input or output will operate as normal until switched active or inactive by a
timetable setting. Switching it active will set it permanently active, while switching it
inactive will set it permanently inactive. The state will continue until another
timetable setting switches it back to normal.
However, it is recommended that special conditioning be used to modify the
operation of the controller rather than these time switch functions, see 26.3.6. These
functions have been retained to allow easier upgrade of existing configurations.
Their use on new configurations is not recommended.
26.3.2 Introduce Alternative Maximum & Priority Timesets
The standard maximum green times for phases (Set A) and standard Priority times
(Set 0) will be effective until switched by a timetable setting.
There are eight maximum green timesets (A to H) and four Priority plans (Sets 0 to
3) available. Switching an alternative maximum green timeset A to D active will
automatically switch the corresponding Priority plan 0 to 3 active. Maximum green
timesets E to H call up priority sets 0 to 3 again.
All phase maximum green timings and all Bus Priority unit timings are switched
when an alternative maximum facility is introduced. Therefore, any maximum green