Westermo RM-505U-2-E - Manual (Page 13)

User Manual
MAN_505_1.7.DOC Page 13
2.3.4 Setpoint Status
The setpoint status is an internal status value, calculated by comparing the analogue input to two
configurable setpoint values. The setpoint status turns ON when the analogue input moves below
the low setpoint value, and turns OFF when it moves above the high setpoint value. The high
setpoint percentage must always be greater than, or equal to, the low set point.
The internal setpoint status will be determined every time an analogue measurement is taken.
The setpoint status is treated as a digital signal and its value is transmitted according to the rules for a
digital input.
2.3.5 Low Battery Voltage Alarm
If the voltage of the internal battery supply falls below 2.9 volts, the internal battery voltage alarm
will turn on.
The Low Battery Voltage Alarm is treated as a digital signal and its value is transmitted according to
the rules for a digital input.
When the a low battery condition occurs, the low battery status will need to be reset - refer to
section 5 of this manual.
2.3.6 Communications Failure
The 505U cannot provide an indication that its transmitted messages have not been received
successfully.
This indication is however available at the receiving 105U by using the 105U Output Reset on
Comms Fail function. To use this function, map an input that is not being used on the 505U to a
spare output on the 105U. The unused input can be an internal input such as the Low Battery status
or Setpoint status, or even the analogue input as this can also be mapped to a digital output.
Configure the 505U so that the digital output at the 105U is normally on - you can configure an input
to output mapping to be inverted or direct.
If you configure a reset time to the 105U output, then this output will turn off if it has not received an
update message from the 505U within that time. The 105U output is effectively a "Communications
OK" output - on when communications are OK, and off during communications failure. Note that
the maximum output reset time at the 105U is 32 minutes, so the update time for the 505U input
must be less than this. It is generally a good idea to set the update time to less than half of the reset
time. Then, the 105U must fail to receive two consecutive update messages - it is possible to miss
one update message because of random noise, but two consecutive failures means that there is a
system failure. For example, if you wish to have a failure alarm within 10 minutes of a system failure,
set the output reset time at the 105U to 10 minutes and the update time at the 505U to 4.5 minutes.