Connect an RS485 / Modbus RTU device

RS485 (Modbus RTU) devices are read by a gateway on the same bus.

Protocol: rs485 · Requires: a gateway

Connection fields:

Field Meaning
modbusId The slave/unit ID on the bus (1–247)
baudRate Bus speed (e.g. 9600, 19200) — must match the device
dataBits Usually 8
stopBits 1 or 2
parity None, Even, or Odd — must match the device (many meters use Even)
tickDuration Publish interval in ms — how often readings are sent to Synacl (minimum 10000)
readIntervalMs Optional. How often the gateway reads the device; drives gateway-side alerts and macros

Steps

  1. Wire the sensor's A/B lines to the gateway's RS485 port; match baud rate, parity, and unit ID.
  2. Add a device with protocol rs485, select the gateway, and enter the fields above.
  3. Define a tag per register you want to read (with scaling/units as needed).

Seeing modbus/timeout events? Check wiring, modbusId, baud rate, and parity. See fault events.

More in Devices
Devices vs. gateways
When you need a gateway, and when a device can talk to us directly.
Device parameters (tags) explained
Tags are the named measurements a device reports — what widgets bind to.
How device online/offline status works
A device is online if we've seen a message in the last 90 seconds.
Alert thresholds (and the yellow dot)
Set a high/low range on a tag; the device dot turns yellow when a reading goes out of range.
Why a device gets suspended
Repeated rate-limit violations suspend a device temporarily — here's the cycle.
Editing, moving, and deleting a device
Change a device's name, connection settings, gateway, or remove it.