User's Manual

905U-K.MAN Rev. 1.1 January 2002
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ELPRO Technologies Pty Ltd Page 11
2.3.1 Digital Inputs
A digital input can be an external digital input or an internal status input (setpoint status or
low battery alarm).
The 905U-K will transmit the value of the digital input whenever it changes from off to on or
from on to off. A paralysis time may be configured to prevent another transmission within
this time. The 905U-K will also transmit an update message if a message has not been
transmitted for that input within an “update time”.
There are two update times for each digital input - one for when the input is on, and one for
when the input is off. Each update time may be configured between 10 seconds and 5 days.
For example, a digital input may be configured to update every 1 day when the input is off,
but update every 10 minutes when the input is on. If an update time of zero (or less than 10
seconds) is selected, then no update messages will be sent.
Overview:
• Input value transmitted on input change
• Update message if the input value has not been transmitted within the configured update
time for that input (10 seconds - 5 days)
• Separate update times for on and off status for digital inputs
• After each transmission, further transmission for that input is disabled for the paralysis time
(0 – 127.5 sec).
2.3.2 Pulse Inputs
Each pulse input is counted and the total count value is transmitted as a 16-bit value. A
“sensitivity” value is configured for each pulse input (0 - 32 000). Whenever the pulse count
has increased by this value since the last transmission, the 905U-K will transmit the new
pulse count. In addition, an update transmission of the pulse count will be transmitted if the
pulse count has not been transmitted for the update time. If an update time of zero is
selected, then no update messages will be sent.
When the 905U receives the input count message, it will compare the input count to its own
output count (the count of output pulses), and will then output pulses until the two counts are
the same.
The maximum pulse input is 1000Hz (3 msec minimum on-time and off-time). There is no
minimum pulse rate. For pulse rates higher than 1Hz, the power consumption will increase
slightly. For pulse rates higher than 10 Hz, the “Fast Pulsed Inputs” option should be selected.
This increases power consumption of the module further.
If the pulse input message is sent to a host device, it is important to note that the count value
transmitted is an absolute value. The only time that it resets is when the 16-bit accumulator
"rolls over" (exceeds 65 535).
Overview:
• Pulse inputs are counted.
• Pulse count is transmitted when the count has increased by the sensitivity amount since
the last transmission.