User's Manual

Chapter Three Operation
man_905_2.0.doc Page 29
output pulse will be output evenly over the pulse output update time which is configured in the
module. For example, assume that 905 module receives a pulse input update message from the
remote 905 module, and the difference between the pulse input count and the pulse output count is
12 pulses. The 905 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 905 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 corresponding to 20mA
output may be configured by the user.
3.1.3 Analogue Set-points
On 905-1 modules, the “AI 1” input may be used to trigger the analogue set-point status. High set
point and low set point levels are configurable. This set-point status turns ON when the analogue
input moves below the low level, and turns OFF when it moves above the high level. The high level
must always be greater than, or equal to, the low level set point. This set-point status may be
mapped (inverted, if required) to any output in the network. The set-point status is effectively an
internal digital input.
On 905-2 modules, each analogue input has set-point values for controlling digital outputs. The