Building Automation

Modbus Universal— RTI XP Driver

Read and control Modbus TCP devices and RS-485 gateways from RTI: energy meters, solar inverters, battery systems, relay boards, HVAC gateways and PLCs, with built-in device presets.

Version
v2.0.0
Updated
Oct 16, 2026
Licensing
Per-processor

About this driver

Two-way RTI control and monitoring for Modbus TCP devices and RS-485 gateways, the protocol behind most commercial and energy equipment. The driver polls registers and coils, decodes them into RTI system variables, and writes registers and coils on command. The parts of Modbus that usually take an afternoon are plain settings: the addressing base (the 0-based protocol address vs the 1-based register numbers printed in manuals), data types and word order, scale and offset, and the device's Unit ID. Device presets fill in the register map for Eastron SDM120 and SDM630 meters, SolarEdge or Fronius (int+SF) inverters with SunSpec scale factors handled, Victron GX systems, and the Waveshare 8-channel relay board, plus a thermostat register-map template (read the temperature, write an exact setpoint, mode or fan) and a 16-relay template to start from. Several RS-485 devices behind one gateway can share an instance through a per-point Unit ID, and gateways left in transparent mode work through the RTU over TCP setting. Every reading is marked current or not: when a read fails, the value is blanked instead of showing an old number as live, and a device that stops answering is listed by its Unit ID. A write pressed while the connection is down is delivered when it returns within 30 seconds, or reported as a Write Error with the point and the reason. Up to 64 points per instance, and one license covers every instance on the processor.

What's included

  • Reads and writes holding registers, input registers, coils and discrete inputs over Modbus TCP, or RTU over TCP for gateways in transparent mode
  • Presets: Eastron SDM120 and SDM630, SolarEdge or Fronius (int+SF) with SunSpec scale factors, Victron GX, Waveshare 8-channel relay, plus a thermostat register-map template and a 16-relay template
  • Data types as settings: 16, 32 and 64-bit integers and floats in every word and byte order, float16, text, a single bit or byte of a register, with scale and offset
  • Per-point Unit ID: several RS-485 devices behind one gateway in one instance; a device that stops answering is listed while the others keep reading
  • Never shows a stale value as live: each point carries a Current flag, failed reads blank the value, and Read Error and Write Error events report what went wrong
  • Value maps (0=Cool, 1=Heat) and not-available codes, plus timing settings for slow devices and gateways
  • Tested on a real RTI XP-6: automatic reconnect with backoff, a hung connection abandoned after 10 seconds, about 1% of the processor with a meter preset
  • Includes a ready-made sample project (RTiPanel iPad and iPhone, RTI Virtual Panel): Status, Points and Relays pages
  • One license per processor covers every instance; 120-minute MAC-locked free trial

What you should know before buying

  • Each instance handles up to 64 points on one device or gateway. Add an instance per device or gateway.
  • RS-485 (serial) Modbus devices need an RS-485 to Ethernet gateway; the driver does not connect to serial ports.
  • Some devices accept only one Modbus connection at a time. If another system already polls the device, check its connection limit first.
  • On an XP-6, a large map whose values change constantly (around 64 points) uses about 5 to 7% of the processor at the default 2-second poll. A longer poll interval lowers it.

How licensing works

  1. Download the driver (free — button on the right), install it in Integration Designer, and load to your processor. It runs unlocked for a total of 120 minutes of run time for compatibility testing. The clock is cumulative, so it does not reset when the processor reboots.
  2. Buy a license here, then sign in and enter your processor's MAC address on your account page. We issue a signed license key bound to that MAC.
  3. Paste the key into the driver's configuration. The trial wall goes away and the driver runs unlocked indefinitely.

Not enough time to finish testing? Email support@customcontroldrivers.com and we will give you more time.

Need a custom driver? Suggest one or email support@customcontroldrivers.com.