What Protocol Conversion Is
Protocol conversion is the process of translating data between two incompatible communication protocols using a gateway. In building automation, this typically means bridging field-level devices (PLCs, meters, controllers) to supervisory systems that speak a different protocol.
Common Conversion Patterns
| Source Protocol | Destination Protocol | Typical Application |
|---|---|---|
| Modbus RTU | BACnet/IP | Meters, VFDs → Building Management System |
| EtherNet/IP | BACnet/IP | PLC → BMS crossover projects |
| Modbus TCP | BACnet/IP | IP-connected power meters → BMS |
| Veeder Root | BACnet/IP | Tank monitors → BMS |
| BACnet MS/TP | BACnet/IP | RS-485 controllers → IP backbone (routing) |
What a Gateway Does
A protocol conversion gateway:
- Polls or subscribes to data on the source protocol side
- Translates values using a point map (addressing, data types, scaling)
- Serves or pushes the translated data on the destination protocol side
Chipkin Products
| Product | Use |
|---|---|
| QuickServer | Current-generation gateway platform |
| FieldServer | Legacy and specialty gateway platform |
[!TIP] For new projects, QuickServer is the recommended starting point. FieldServer is used for legacy configurations and specialty protocols.
Common Problems
- Points map incorrectly between protocols — Register/object addressing mismatch or wrong data type in the point map. See Modbus to BACnet Protocol Conversion Guide for a worked example.
- Scaling is wrong on destination side — Source value is raw (counts, bits) and the destination expects engineering units. Check the scale factor in the point map configuration.
- Source device stops responding after gateway connects — Gateway polling rate too aggressive for the device. Reduce poll frequency in the gateway configuration.
- EtherNet/IP to BACnet integration issues — Assembly object size or data path mismatch. See EtherNet/IP Integration Guide.