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memory is turned 'ON' by pressing button C and 'OFF' by pressing button D.
The new transmission will only occur if either memory has changed since the last
transmission.
If buttons B & D are replaced by two diodes and one button (B), the option
functions as a nursecall with button B being the cancel button.
10
Two button/two channel mode.
Both 'MODE 0' and 'MODE 1' switches OFF. Input C must be linked to Gnd.
Two buttons can be connected - button B from input B to +ve and button A from
input A to +ve.
This functions similarly to 9 above except that the memories are automatically
turned 'OFF' at the end of a transmission.
11
Self test mode.
This mode is selected by separate DIL switch labelled 'TEST'.
If selected, it overrides any other mode selection and repeatedly sends a
transmission, consisting of 12 site/unit code bits read directly and continuously from
the DIL switches. Changing the DIL switches during the transmission will cause an
immediate change in the transmitted data.
FAST MODE OPERATION
The DIL switch labelled FAST gives two options for the speed at which the inputs
are scanned which also has a direct affect on battery life.
If the FAST switch is off, the inputs are scanned every 100mS. This is suitable for
most types of input except very fast push buttons and gives battery life of typically
7 years. If the FAST switch is 'ON' the inputs are scanned every 20mS, with a
reduced battery life of typically 4 years.
If the speed mode is changed, it is necessary to switch off the transmitter and wait
2-3 seconds before switching on again, before the new speed comes into effect.
OTHER OPERATIONAL DATA
a.
In all operational modes except 7, the bleeper will produce a small click every
time any input (A, B or C) changes state.
b.
If any DIL switch is changed, the first transmission immediately after the
change will use the old switch data.
Always 'throw away' the transmission following a DIL switch change.
c.
Most modes of operation will not allow a second transmission of the same
type as its predecessor within 500ms. This is to avoid several transmissions of
the same type causing a false 'low battery' signal at the receiver.
d.
Switching on/off.
The DIL switch labelled ON/OFF isolates the battery. It takes up to 15
seconds for the circuit to correctly function after switching on.
Part No. 495940 Issue 2
5
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