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16.
Pulse count and GenII telemetry
The pulse count transmitters GC62 and GD67/GD68 employ the same
measuring and transmission techniques.
Transmitter
At the transmitter pulses are counted continuously to a maximum of 65,535.
When 65,535 is reached the counter is reset to zero and starts counting
again.
At the time of transmission the value in the counter is transmitted.
The transmission interval is normally the logging interval / 6.
Receiver
The last valid value from each transmitter is held by the receiver in a register.
The device connected to the RC250 must calculate the difference between
the previous and current values to determine the number of pulses that
should be used.
If a no
–
data condition occurs
Incidence of frequent no-datas (no transmitted data received by the receiver)
should always be investigated as a matter of urgency as no-datas could be an
indication of radio coverage issues.
The period that the receiver can cope with consecutive no-datas and still
record a valid value when a transmission is eventually received is 65,535
pulses. The actual period of time is therefore linked to how frequently pulses
are expected from the measuring sensors.
For instance, in the case of The PRO1D electricity meter, the device is rated at
45A max and provides 2000 pulses per KWh.
A kettle rated at 2,500W/2.5kW will consume (assuming AC voltage is
240VAC) 10.41A. So if were left boiling for 12 hours it would consume
2.5kW/12 = 30kWh.
This equates to 30 x 2000 pulse from the PRO1D = 60,000 pulses, indicating
that under the conditions of this unlikely example, if a valid transmission were
received after 12 continuous hours of no-datas the receiver would self-correct
and there would be no inaccurate values in the receiver
’s data
.
