Section 3: Operation - scope SCPUHF User Manual

Section 3: Operation

The controller is in the sleep mode for most of the time, and will wake up every 1.2 seconds
to read the inputs. If the RESET input is closed, the inputs are effectively disarmed and no
pages will be sent, regardless of the input states. If the RESET input is open, the zone inputs
will be compared to the states they were in when the board was powered up, or the last time
the RESET input was closed.
To change the state of any or all zones, ensure that the zones are set in their standby mode
and close the RESET input. This will cause the Green TX LED to light momentarily when the
state of the inputs is being read. The transmitter has now been programmed to accept the
input condition as standby. Changing the condition of any input will cause the transmitter to
send a page applicable to that input. Inputs must change state for a minimum of 1.5 seconds
to ensure activation of the transmitter, although any changes in state of more than 300
milliseconds may initiate a transmission for that zone. This will depend on the time position of
the processor relative to its wake up command. This requirement allows the standby current
to run at less than 300uA. It also ensures freedom from possible inductive false triggers
which could be caused by mains spikes etc.
Any zone which remains in the triggered state will cause the Green TX LED to blink every
1.2 seconds. When this is not flashing it indicates that all zones are clear. If the Green TX
LED continues to blink, it indicates that one or more inputs remain in a triggered state. If you
are sure that all zones are inactive and in their standby condition and the Green TX LED is
blinking, you must perform a RESET to update the inactive status of the unit. You must close
the RESET input until the Green TX LED lights, or the new status will not have been
reprogrammed. The maximum required close time for the RESET is 3 seconds.
The system is configured so that only one input can be triggered at one time. It is therefore
necessary to hold inputs from potential multiple trigger conditions for longer periods.
1 potential input at one time requires 1.5 seconds trigger
2 potential inputs at the same time requires 3 seconds trigger
3 potential inputs at the same time require 4.5 seconds trigger
4 potential inputs at the same time require 6 seconds trigger.
Transmission time for any message should not exceed 1.5 seconds. All triggers are
individually flagged and if the transmitter is set to repeat, all will repeat until each input
reverts to its original state.
Problems and Fault Finding.
1 Check that the input cables are connected to the active zones.
2 For Zones 1-3, ensure that no voltage is present on the input cables. Also, check that
cable runs are not excessive (preferably less than 10 metres) and are not in close
proximity to other mains or telecoms cabling.
3 Check that the pagers are at least 3 metres from the transmitter and aerial.
Under certain conditions it is possible to flood the pager receivers and corrupt the
data received.
4 Check that the pagers have the battery installed with the correct polarity and are
correctly powered up.
SCPUHF
SCPUHF Paging Transmitter System
10
Issue 2