Building management system wants to read values from our SCADA via Modbus

[DataStream]

Our facility team uses a separate building management system (BMS) and they want about 30 values from our Omnivex SCADA: chiller status, a few temperatures and the main energy readings. The BMS can only act as a Modbus TCP master. It cannot use OPC or MQTT.
The values already exist in our SCADA as tags read from three different PLCs. I would prefer that the BMS doesn't connect to the PLCs directly, for safety reasons. Can Omnivex SCADA act as a Modbus server for the BMS, and how do I get the existing values into it?

[Technical Support]

Yes. Omnivex SCADA has a Modbus TCP Slave channel type for this.
1. Create the slave channel
In the Tag Editor, right-click Created Channels, select Add Channel and choose Modbus TCP Slave. In Channel Info set IP (the SCADA server's network interface that the BMS will reach), Port and Request Time. Tell the facility team which IP and port to use.
2. Frames and tags
Add a frame with Function Type, Data Type, Start Address, Quantity and Slave ID, then add one tag per value. This creates your "address map" for the BMS. Write the map down as a table (address, name, data type, unit, scaling); the BMS integrator will need it.
3. Copy the PLC values into the slave tags
Use the Data Transfer Editor: right-click Created Data Transfers, select Add Data Transfer, set a Request Time (update interval), then add tag pairs with Source Tag (the PLC tag) and Destination Tag (the slave tag). The SCADA then keeps the slave tags up to date.
Practical advice
- Use the same data type and scaling on both sides, or document the multiplier. Word order of floating point values is a common source of strange numbers on the BMS side, so test one value first.
- Expose only what the BMS needs. If the BMS should only read, don't map control values into the slave frame.
- Keep the BMS on the network segment your IT team defines; the SCADA becomes the single gateway, as you intended.
Documentation: https://greensoft.ai/documentation/o...ion-protocols/