Operation Of A Bacnet Module - Mitsubishi Electric MELSEC iQ-R User Manual

Operation of a BACnet module

Operation at startup
A BACnet module initializes an access block for BACnet monitoring with '0' at the startup of the module.
Cyclic operation
• A BACnet module sends ReadProperty(Multiple) services with a set cycle to sample property values of a monitoring target.
• When a reply to the ReadProperty(Multiple) service is received from the monitoring target, the received data is discarded
while the CONTROL of an access block for BACnet monitoring is other than '0' (idling).
• When a normal response (ComplexAck) is received from a monitoring target while the CONTROL of an access block for
BACnet monitoring is '0' (idling), the received data is stored to the access block for BACnet monitoring, and '1' (data
reception) is stored to the CONTROL.
• When an error response is received from the monitoring target, error information is stored to the STATUS, and '2' (error
end) is stored to the CONTROL.
Precautions
• Be sure to store '0' (idling) to the CONTROL after reading the received data.
The Status and Data are not updated while the CONTROL is '1' (data reception).
• With the following setting, the STATUS and Data of an access block for BACnet monitoring can be updated
(overwritten) every time when new data is received. This makes it unnecessary to store '0' to the CONTROL
after reading data.
Set '1' to "RecDataOverwriteMonitor" in [Settings]  [Basic Information]  [BACnet Detail Setting] button 
[Edit] button  "Interaction".
• The Status and Data can also be updated when a COV notification or an Event notification is received from
the property which is monitored by an access block for BACnet monitoring.
(COV notification)
Set '1' to "MonitorDataSetByCOV" in [Settings]  [Basic Information]  [BACnet Detail Setting] button 
[Edit] button  "Interaction".
(Event notification)
Set '1' to "MonitorDataSetByEvent" in [Settings]  [Basic Information]  [BACnet Detail Setting] button 
[Edit] button  "Interaction".
■ When monitoring a PresentValue property
When a PresentValue property is specified as a monitoring target, a StatusFlags property is automatically read at the same
time. To check the reliability of the PresentValue property value, monitor the StatusFlags property with the BACnet monitoring
function, and check if an error (InAlarm, Fault, or OutOfService) occurred in the StatusFlags property.
■ When monitoring a SystemStatus property
When a SystemStatus property is specified as a monitoring target, monitoring is started at any of the following timings.
• The cycle specified to "Interval (Sec)" when an access block for BACnet monitoring is assigned (Page 140 How to use
the BACnet monitoring function)
• The value of a SystemStatus property is changed
*1 The value of a SystemStatus property is changed at any of the following timing.
 When the notification of a BACnet status (join/leave) is received from a monitoring target BACnet device
 When I-Am services could not be received from a monitoring target BACnet device with the cycle set to "CheckAliveInterval" in
[Settings]  [Basic Information]  [BACnet Detail Setting] button  "Who-Is"
*1
1 FUNCTIONS
1.6 BACnet Monitoring Function
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