Variable-Speed Drives and Remote Access: Challenges and Opportunities
Variable-speed drives (also known as frequency converters or VFDs—Variable Frequency Drives) are ubiquitous in industry: pumps, fans, compressors, conveyors, and machine tools. A production facility may have dozens, or even hundreds, of them. The ability to diagnose and reconfigure them remotely is a significant driver of efficiency.
The leading manufacturers—ABB, Danfoss, Schneider Electric (Altivar), Siemens (SINAMICS), WEG, Mitsubishi—all offer network communication options that enable remote access via an industrial 4G VPN router.
Communication Protocols by Brand
| Manufacturer | Series | Modbus RTU | Modbus TCP | PROFINET | EtherNet/IP |
|---|---|---|---|---|---|
| ABB | ACS310/550/880 | Yes (RMBA-01) | Yes (FMBT-21) | Yes | Yes |
| Danfoss | VLT FC102/302 | Yes (native) | Yes (MCA 120 option) | Yes | Yes |
| Schneider | Altivar 32/320/630 | Yes (native RS-485) | Yes (VW3A3616 option) | Yes | Yes |
| Siemens | SINAMICS G120/S120 | Yes (CU240E option) | Yes (via PROFINET) | Yes (native) | Partial |
| WEG | CFW300/500/700 | Yes (native) | Yes (option KW090RS) | Yes | Yes |
| Mitsubishi | FR-E800/A800 | Yes | Yes | Yes | Yes |
Remote Access Architecture for Modbus TCP Drives
The simplest architecture for remote access to Ethernet drives:
- The drive is configured with a static IP address on the local network (e.g., 192.168.1.20)
- A 4G VPN router is connected to the same industrial Ethernet switch
- The VPN tunnel provides access to the local network
- The manufacturer’s software (DriveStudio, MyDrive, SoMove, STARTER/Startdrive) connects via the drive’s IP address
For Modbus RTU (RS-485) drives, a router with a built-in RS-485 port is required for RTU-to-TCP conversion within the VPN tunnel.
Parameters Accessible Remotely on a Drive
Via Modbus TCP or the manufacturer’s protocol, the remote engineer can access:
Monitoring:
- Output frequency (Hz) and motor speed (rpm)
- Output current (A) and voltage (V)
- Heat sink temperature (°C)
- Power consumption (kW)
- Fault log with timestamps
- Total operating time (hours)
- Energy meters (kWh)
Programming (Configuration and Control):
- Speed reference (setpoint)
- Acceleration/deceleration ramps
- Motor protection parameters (rated current, thermal protection)
- Start/stop control (with safety precautions)
- Fault reset
Developer Tools for Remote Access
ABB — DriveStudio / Drive Composer DriveStudio (previous generation) and Drive Composer (current) connect via local USB or Modbus TCP over the network. For remote access, configure the drive’s IP address in "Add new drive > TCP/IP connection." Access all parameters, the oscilloscope, and the fault log.
Danfoss — MyDrive Connect MyDrive Connect supports Modbus TCP and PROFINET connections. Use a VPN to enter the VLT’s IP address and access parameter groups, fault logs, and usage statistics.
Schneider — SoMove SoMove connects via Modbus TCP (Ethernet card option on Altivar) or via Modbus RTU (USB-RS485 cable). When connecting remotely via Ethernet VPN, the full interface is available—including configuration backup and restore.
Siemens — STARTER / Startdrive STARTER (TwinCAT 2) and Startdrive (integrated into TIA Portal) connect to SINAMICS via PROFINET or USB. Via VPN, the PROFINET connection over Ethernet works transparently.
Security of Remote Access to Drives
- Never expose Modbus TCP (port 502) directly to the Internet: Modbus has no native authentication mechanism
- VPN tunnel required for all access from outside the site
- Coordinate with the on-site team before making any parameter changes or issuing start/stop commands
- Drive password: Most drives allow you to protect settings with a PIN—enable this protection
- Traceability: Log all changes (who, when, which setting, before/after)