Moxa MGate 5101-PBM-MN PROFIBUS to Modbus TCP Gateway

Reading PROFIBUS devices from a Modbus TCP SCADA or PLC

The Moxa MGate 5101-PBM-MN is a one-port gateway in which a PROFIBUS DP-V1 master side serves PROFIBUS drives and instruments, and the Ethernet side acts as a Modbus TCP client or server for SCADA systems and PLCs. This lets plants with PROFIBUS field devices, common in oil and gas, power and process automation, feed data into Modbus-based supervisory systems without replacing devices. The MGate Manager utility has an AutoScan function that detects the connected PROFIBUS slaves and their I/O modules and builds a data-mapping table to guide configuration of the Modbus master. Dual DC power inputs and a relay output for power status add reliability.

Technical specifications

Ordering codes

Key features for PROFIBUS-to-Modbus TCP integration

• PROFIBUS DP-V1 master: the gateway polls PROFIBUS slaves itself, so drives, remote I/O and analysers can be read without a PROFIBUS-capable PLC.
• Modbus TCP client and server: the Ethernet side can serve data to several SCADA or HMI clients at once, or push data to a Modbus TCP server.
• AutoScan in MGate Manager: detection of connected slaves and their I/O modules shortens commissioning and reduces typing errors in the mapping table.
• Redundant power and relay alarm: two DC inputs with a relay output for power status support high-availability panels.
• Hazardous-area approvals: ATEX, IECEx and Class I Division 2 listings as printed on the datasheet allow use in classified areas when installed according to the certificates.

Typical architectures

Migrating a legacy PROFIBUS plant

When an old PLC with a PROFIBUS master is replaced by a controller or DCS that uses Modbus TCP, the MGate can take over the master role on the existing PROFIBUS segment. Field devices, cabling and GSD-based configuration stay in place, which avoids the cost and downtime of replacing every instrument.

Adding monitoring to a packaged unit

A compressor skid, a variable speed drive line-up or an analyser house delivered with PROFIBUS devices can be connected to a plant-wide Modbus TCP SCADA via the gateway. Note that because the MGate is a master, it should not be added to a segment already controlled by another PROFIBUS master unless the network design explicitly allows multiple masters.

Selection guidance

• Choose the standard MGate 5101-PBM-MN for indoor control rooms and air-conditioned panels (0 to 60 °C).
• Choose the MGate 5101-PBM-MN-T for outdoor cabinets, RTU kiosks or locations without reliable cooling (−40 to 75 °C).
• Total the input and output bytes of all slaves and keep them within 1536 bytes each way.
• Confirm the PROFIBUS baud rate supported by every slave; the gateway works from 9600 bps to 12 Mbps.
• If the field devices are PROFIBUS slaves but the host is a PROFINET controller, a different gateway type is needed.

Installation and maintenance in Oman and GCC sites

Gateways in oil and gas fields of interior Oman often sit in RTU shelters or outdoor junction boxes where internal temperatures climb well above 50 °C in summer, making the wide-temperature -T model the safer choice. The IP30 metal housing needs an enclosure that protects against windblown dust and sand. Use properly terminated PROFIBUS connectors with active termination at both segment ends, keep PROFIBUS cable away from VFD motor cables, and bond cable screens to a clean earth. Back up the configuration with MGate Manager after commissioning and after every change, and record the firmware version so a spare unit can be loaded quickly if replacement is needed.

What to include in your RFQ

• Exact model: MGate 5101-PBM-MN or MGate 5101-PBM-MN-T.
• Number and type of PROFIBUS slaves and their I/O sizes.
• Modbus TCP role required (client, server or both) and the SCADA or PLC used.
• Hazardous-area classification of the installation location, if any.
• Quantity and delivery location.

Engineering and commissioning notes

The gateway is a PROFIBUS master, so it cannot replace another master on the same segment; use it where the PLC no longer speaks PROFIBUS or where a second reader is needed. Count the I/O of the PROFIBUS slaves against the 1536-byte limits before ordering, and keep PROFIBUS cable, termination and baud rate within the segment limits stated by the device manufacturers. The web console shows I/O data and logs of Modbus and PROFIBUS connection events, and the relay can signal loss of one power input. For Modbus RTU devices on a serial bus, use a model such as the MGate MB3170 instead. Seven Star LLC, an independent supplier in Muscat, quotes the exact code you need; confirm GSD files for your slaves and the temperature range before ordering. The datasheet (version 1.3) is attached, and related products are in Industrial Communications. Maintenance is supported by a web console and a Telnet console that both support encryption (HTTPS and SSH), by firmware logs of Modbus and PROFIBUS connection events, and by PROFIBUS and Ethernet status LEDs. The relay output signals the status of the power inputs, which gives maintenance staff an extra alarm. Use the import and export functions of MGate Manager to keep a copy of the configuration with the project documents. Environmental tests listed include shock (IEC 60068-2-27), vibration (IEC 60068-2-6 and -64) and free fall (IEC 60068-2-32). Web and Telnet management are encrypted with HTTPS (TLS 1.3) and SSH, authentication is by local database, and SNMPv3 is supported. Data size is 1536 bytes in each direction, so large PROFIBUS networks should be checked against that limit before commissioning.