Modbus MFU Option Card Installation Manual
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Publication PUB091-003-00_0119
Running Open
Whenever the actuator motor contactor used to drive the actuator in
the opening direction is energised this bit will be true (1).
Remote Selected
This bit is true (1) when the actuator three position remote/local
stop/local selector is in the Remote position. The selector must be in
this position for Modbus control to be permitted.
Local Stop
The actuator three position selector passes from Local to Remote or
Remote to Local through the Local Stop position. The switch can also
be placed in Local Stop. When the switch is in the Local Stop position
this bit will be true (1). Remote control of the actuator is not possible
when the selector is in this position.
Local Selected
This bit is true (1) when the actuator three position remote/local
stop/local selector is in the Local position. Remote control of the
actuator is not possible when the selector is in this position.
Thermostat
If the temperature of the motor windings rises above the thermostat
trip value, the thermostat contact will open and this signal will be
present (1). There are no adjustments for the temperature at which
the thermostat trip operates. The motor will be stopped if the
thermostat trips. Only once the motor has cooled down and the
thermostat has reset itself can a new Remote, Host or Local
command to move the actuator be carried out. A setting on the
actuator main board allows the ESD command to override the
thermostat. The bit will remain set at logic 1 until the motor cools down
and the thermostat resets itself.
Monitor Relay
This signal is true (1) when actuator remote control is not available.
The actuator Monitor Relay status is a composite signal for several
alarms. This signal will be set true if the actuator selector is in Local or
Local Stop (not in Remote) or if the thermostat trips. The mains supply
is also monitored and if one of the three phases is lost this bit is set. If
the actuator is operated from a single phase supply and this is lost
then communications with the actuator will also be lost. Where a 3
phase supply is used, if the phase associated with the control circuits
is lost then communications with the actuator will be lost.
Valve Obstructed
This bit will be true (1) if the actuator stops in mid travel when not
expected to do so after receiving a command to move. If the actuator
torque exceeds the trip value set during commissioning then the motor
will stop and motion will cease. The reason for the actuator stopping
will be the high torque due to an obstruction and not a ‘Stop’ signal or
reaching the desired setpoint position. (This could indicate a
thermostat trip in a ROMpak actuator).