105 Radio/Serial Telemetry Module
User Manual
Page
28
©
January 2004
configurable. The absolute pulse count is transmitted. If the PI is transmitted to a PO on a
105 module, then the pulse outputs are re-created from the
accumulated
pulse count.
Rollovers of the pulse count thru zero are catered for. If a transmission is missed, the pulse
output will still be re-created when the next accumulated value is transmitted. This ensures
that no pulses are lost due to communications failures. If the PI is transmitted to a 105U-C
interface module, then the accumulated pulse count is stored in the 105U-C for interfacing to
the host device.
The following diagram shows how pulse inputs are re-created as pulse outputs. For pulse
outputs, the 105 module keeps two counters in memory - the pulse input count received
from the remote 105 module, and the count of output pulses. When the 105 receives an
update of the input pulse count, it will output pulses until the output pulse count is the same
as the input pulse count. The output pulse will be output evenly over the pulse output update
time which is configured in the module. For example, assume that 105 module receives a
pulse input update message from the remote 105 module, and the difference between the
pulse input count and the pulse output count is 12 pulses. The 105 will then output the 12
pulses evenly over the next minute (if the pulse output update time is 1 minute).
The default values for the pulse input update time and pulse output update time is 1 minute.
In this case, the output pulses are effectively 1 minute behind the input pulses. These update
times may be changed by the user. The pulse output update time should not be set to be more
than the pulse input update time. Note that the maximum pulse rate for both inputs and
outputs is 100Hz.
Input
Pulses
Time
Output
Pulses
PI update time
PO update time
Time
As well as accumulating the pulse input, the 105 module will also calculate the rate of
pulses.
Pulse rates
are treated as an “internal” analogue input and are configured with
analogue sensitivities for change-of-state transmissions. The maximum pulse rate