Issue
Is it possible to host the same third party BACnet device on the AS-P private networks on multiple automation servers, which are all connected on the same network?
Product Line
EcoStruxure Building Operation.
Environment
Building Operation Automation Server Premium
Cause
The design in question is a 3-storey accommodation building which includes 1 x BMS panel/AS-P per level. However, only 1 x Mitsubishi EW-50E BACnet gateway is being provided for the building.
Resolution
It is possible to host the same 3rd party BACnet device in multiple AS-Ps. Some caution is required, however, because if the user makes changes to an object in that device through one AS-P, that change may not be reflected in other AS-Ps.
When viewing runtime variables, such as 'Value' and 'Status Flags', this is not a problem because the EBO server will always get new values from the wire. Where the problem can present itself, is when changes are made to configuration values because these are only updated in an EBO server during an upload operation.
For example, if you set the hi-limit and low-limit values in an analog-value object from one AS-P, those values will not be updated in other AS-Ps until you do an upload of that object.
The other place where this problem may present itself is in schedules. An EBO schedule only writes values to a device when that value changes. For example, if you have a schedule configured to change the setpoint to 65 degrees at 5pm, EBO will only write a value of 65 if the current 'local' value is not 65. If this schedule only writes 1 time per day and someone has set the value to 70 from another AS-P, the first AS-P does not realize the value has changed so that schedule will not generate a write request to set the value to 65 (it will stay at 70). However, if you have a program or trend-log monitoring the value, the AS-P will be tracking that value and realize it is not 65 so you will see a write request at the scheduled time.
The system works this way because reading all values of all devices and all objects all the time is simply not practical. As long as the user is aware of how the system is designed, they can avoid these potential issues.
Make sure to use Static IP, so IP do not change, or you get multiple DHCP servers on the same network.
Another alternative is to host the BACnet device in one AS-P only, then using internal bindings to share the data with other AS-Ps.
