If your control cabinet has SEW drives on one side and a PROFIBUS network on the other, the SEW-Eurodrive DFP21B/UOH11B is the direct bridge. If your PLC speaks PROFIBUS and your field device speaks Modbus, the Moxa 4101-MB-PBS is the gateway to compare. Both sit in the industrial networking fieldbus space, but they connect different kinds of equipment.
Quick verdict
Choose the SEW-Eurodrive DFP21B/UOH11B when you need PROFIBUS access to SEW MOVIDRIVE MDX61B or MOVITRAC B drives. It lists at $155.00 and can link up to eight inverters through SBus, so one unit covers a small drive group. The Moxa 4101-MB-PBS, at $869.00, is the better fit when the job is protocol conversion: it is a Modbus-to-Profibus slave gateway. That $714.00 spread reflects the difference between a drive-specific interface and a general-purpose protocol converter.
Side-by-side comparison
| Gateway | Listed Price | Condition | Fieldbus Role | Ports / Speed | Price Position |
|---|---|---|---|---|---|
| SEW-Eurodrive DFP21B/UOH11B | $155.00 | Used | PROFIBUS DP-V1 interface for SEW MOVIDRIVE / MOVITRAC B | Up to 8 inverters via SBus | |
| Moxa 4101-MB-PBS | $869.00 | Open box | Modbus to Profibus slave gateway | 1 port, 230.4 Kbps |
Where each product wins
The SEW gateway wins when your drives are already SEW MOVIDRIVE MDX61B or MOVITRAC B. The Moxa gateway wins when you need one Modbus device to appear as a PROFIBUS slave. With multiple SEW drives, a single SEW gateway can bring them onto the same PROFIBUS network. With one Modbus instrument and a PROFIBUS controller, the Moxa module provides that single conversion point.
Product notes
SEW-Eurodrive DFP21B/UOH11B
If you already run SEW MOVIDRIVE MDX61B or MOVITRAC B inverters, this gateway speaks their language. It connects them to the PROFIBUS side of your network through SBus, and the spec allows up to eight inverters per gateway, so a small cabinet can be brought online with one unit. The operating range of -10 to +60°C and IP20 protection are practical for indoor enclosures. The trade-off is the used condition and the fact that SEW-Eurodrive has discontinued this model, so sourcing a spare later may depend on existing stock. It also needs 24 V DC at 0.3 A. If your drives are not SEW MOVIDRIVE or MOVITRAC B, this is not the right gateway.
Moxa 4101-MB-PBS
The Moxa 4101-MB-PBS takes one Modbus link and places it on PROFIBUS as a slave node at 230.4 Kbps. That makes it the useful middle piece when your controller is on PROFIBUS and your end device is on Modbus. The single-port design is the limitation: if your layout requires connecting multiple Modbus devices to the same PROFIBUS master, you would need more than one of these modules. It operates from 0 to 55°C, which is typical for panel-mounted controls. The 4101-MB-PBS part number is the exact version to match for this drop-in style.
Final choice by use case
If your automation line is built around SEW MOVIDRIVE or MOVITRAC B drives and you want PROFIBUS connectivity, the SEW-Eurodrive DFP21B/UOH11B is the matching bridge. If your setup has a PROFIBUS controller and one Modbus field device, the Moxa 4101-MB-PBS is the protocol converter for that single link. Let the hardware on your network decide which gateway belongs in the cabinet.
