Should you use an explosion-proof router or a DTU?
Use an explosion-proof 4G/5G router when a hazardous-area site must connect several IP devices, route between networks, enforce firewall or VPN policies, or provide a cellular WAN. Use a DTU when the main task is transporting serial data from a PLC, RTU, meter or sensor. In either case, verify the exact certificate, interfaces, cellular bands, operator acceptance and remote-management functions.
Remote wellheads, tank farms, pipeline stations, mines and chemical storage areas often need a connection to SCADA, a control center or an industrial cloud platform. Cellular service can avoid a long private backhaul build, but the edge device must fit both the network role and the classified location.
“Router” and “DTU” are sometimes used loosely. Treating them as interchangeable leads to unnecessary complexity or missing functions.
What an industrial cellular router does
A router moves IP packets between networks. At a remote hazardous-area node, it commonly connects Ethernet devices to a public or private 4G/5G network. Depending on the exact model and firmware, a router may also provide firewall rules, network address translation, VPN tunneling, policy routing, monitoring and failover.
Typical router endpoints include:
· IP cameras;
· Ethernet PLCs and RTUs;
· industrial switches;
· edge computers;
· protocol gateways;
· WiFi access infrastructure;
· several devices on a remote local-area network.
Select a router when the remote site is a network, not merely one serial data source.
What a DTU does
A data transmission unit connects an industrial data interface to a wide-area communication service. In many deployments, the core task is carrying RS232 or RS485 data between a field device and one or more remote servers.
Typical DTU endpoints include meters, PLC serial ports, RTUs, sensors and legacy controllers. The application may use transparent TCP or UDP transport, a supported industrial protocol, or a vendor-specific data channel. Exact mode and protocol support must be verified in the product documentation.
A DTU can be simpler to configure for a narrow serial-data task. It should not be assumed to provide the routing, segmentation or VPN features of a full industrial router.
Router and DTU comparison
|
Decision factor |
Explosion-proof router |
Explosion-proof DTU |
|
Main payload |
IP traffic from one or more devices |
Serial or focused industrial data |
|
Local network |
Often connects an Ethernet LAN |
Usually connects a field interface such as RS232/RS485 |
|
Routing and NAT |
Core role |
Not the primary role |
|
Firewall or VPN |
May be available; verify exact firmware |
May be limited or unavailable; verify |
|
Multi-device site |
Strong starting point |
Suitable only if interfaces and data design support it |
|
Legacy serial instrument |
May need an external gateway |
Natural starting point |
|
Configuration complexity |
Broader network policy |
Focused data channel |
|
Selection evidence |
Network diagram and security policy |
Serial settings, protocol and server details |
MAXON preliminary model map
MAXON confirms that all listed explosion-proof router and DTU models hold GB/T 3836 certificates. Its explosion-proof 4G/5G router category lists:
· MX834-1D: 4G explosion-proof industrial router, Ex db IIB T6 Gb; Ex tb IIIC T80°C Db;
· MX934-1D: 4G explosion-proof industrial router, Ex db IIC T6 Gb; Ex tb IIIC T80°C Db;
· MX844-1D: 5G explosion-proof industrial router, Ex db IIB T6 Gb; Ex tb IIIC T80°C Db;
· MX944-1D: 5G explosion-proof industrial router, Ex db IIC T6 Gb; Ex tb IIIC T80°C Db.
The explosion-proof DTU category lists:
· MX832-1D: 4G explosion-proof DTU, Ex db IIB T6 Gb; Ex tb IIIC T80°C Db;
· MX932-1D: 4G explosion-proof DTU, Ex db IIC T6 Gb; Ex tb IIIC T80°C Db;
· MX842-1D: 5G explosion-proof DTU, Ex db IIB T6 Gb; Ex tb IIIC T80°C Db;
· MX942-1D: 5G explosion-proof DTU, Ex db IIC T6 Gb; Ex tb IIIC T80°C Db.
This family map is for navigation only. The reviewed 4G router pages contain some 4G/5G and NR wording, while accessible tables for the DTUs listed as 5G did not establish NR bands. The exact cellular module and supported bands must therefore be confirmed from the current approved datasheet.
Decide between 4G and 5G from the workload
5G can offer higher capacity, lower radio-interface latency in suitable networks and access to private-network architectures. Those benefits depend on coverage, spectrum, operator configuration, core network, SIM, antenna system and application path.
4G remains appropriate for many telemetry, alarm, meter-reading and moderate remote-access tasks. A stable 4G signal with suitable bands and operator support may provide better project value than a weak or unavailable 5G service.
Ask these questions:
1. What are the sustained and peak uplink and downlink rates?
2. Is the traffic periodic telemetry, live video or interactive maintenance?
3. What latency and outage can the application tolerate?
4. Is public cellular, private LTE/5G or both required?
5. Which exact bands and operators cover the site?
6. Is dual-SIM or multi-operator resilience required?
7. Does the device need a long lifecycle in that region?
Do not specify 5G merely because it is newer.
Verify regional bands and operator compatibility
Cellular products are not globally interchangeable. A modem may support only a subset of the bands used in the USA, Europe or Middle East. The operator may require device certification or an approved module. Private networks use their own spectrum and SIM policies.
For every destination country, confirm:
· modem manufacturer and exact module version;
· LTE and NR bands;
· NSA and SA mode if relevant;
· SIM format, eSIM needs and APN configuration;
· carrier or private-network acceptance;
· cellular, EMC and market-access approvals;
· antenna frequency range and approved installation;
· fallback behavior when 5G is unavailable.
A label stating “5G” is not enough evidence for procurement.
Design the antenna system as part of the product
Metal process structures attenuate cellular signals. The installation may need an external antenna positioned for adequate signal while remaining within the approved hazardous-area assembly.
Evaluate received signal power, quality and interference—not signal bars alone. For LTE/5G, metrics such as RSRP, RSRQ and SINR help diagnose the link. Test the intended operators at the actual mounting location and during representative network load.
Check every antenna, RF cable, connector, isolating component and cable entry against the certification documents. Adding an unapproved antenna can affect both radio compliance and hazardous-area suitability.
Cybersecurity for remote industrial sites
A cellular connection should not expose the OT device directly to the internet. Use a defined architecture with private addressing or a controlled APN, authenticated VPN access, firewall rules, unique credentials, certificate management and logging.
Recommended design questions include:
· Who can initiate a connection to the remote site?
· Which ports and protocols are permitted?
· Where does the VPN terminate?
· How are device identity and credentials managed?
· Can firmware and configuration be updated securely?
· How is access revoked for a contractor or replaced device?
· Are security events sent to a central system?
· Does the design prevent direct access from enterprise users to PLCs?
Place remote access through an industrial DMZ where the site architecture requires it. Disable unused services and management interfaces.
Reliability and data continuity
Cellular coverage can change with weather, congestion, maintenance or antenna obstruction. Design for the business consequence.
A telemetry application may buffer records locally and forward them after reconnection. A video application may require adaptive bitrate or local recording. A critical remote site may use dual SIMs, two operators, a private radio link or wired backhaul. Remember that two SIMs in one modem do not protect against device, antenna or power failure.
Test power recovery, network re-registration, SIM switching, VPN restoration and server reconnection. Define watchdog behavior and remote reset controls carefully so they cannot create a restart loop.
Serial details for a DTU project
For a DTU, record:
· RS232 or RS485 physical interface;
· baud rate, data bits, parity and stop bits;
· two-wire or four-wire arrangement where applicable;
· protocol and message timing;
· server address, port and transport;
· client/server initiation behavior;
· number of data centers;
· buffering and reconnection rules;
· isolation, grounding and surge requirements.
Serial timing errors can appear as cellular failures. Validate the complete PLC-to-server path.
RFQ checklist
- Hazardous-area marking and installation country
- Router or DTU network role
- Local Ethernet, RS232 and RS485 interfaces
- Device count and network diagram
- Protocols, throughput and latency target
- Public/private cellular network and operators
- Exact LTE/5G bands and SIM arrangement
- VPN, firewall and remote-management requirements
- Power, antenna, cable-entry and environmental conditions
- Required certificates and market approvals
FAQ
Can a DTU replace an industrial router?
Only when its exact interfaces and functions cover the application. A DTU is usually selected for focused data transport, while a router manages IP connectivity for a broader local network.
Is 5G necessary for SCADA telemetry?
Often no. Many telemetry workloads fit comfortably within 4G capacity. Choose 5G when verified coverage and specific capacity, latency or private-network requirements justify it.
Can one router connect cameras and PLCs?
Potentially, if its interfaces, throughput, routing and security features meet the design. Segment traffic and calculate peak uplink demand rather than combining devices without a capacity plan.
Does an explosion-proof router still need a firewall?
Yes. Explosion protection addresses ignition risk; it does not provide cybersecurity. Apply firewall, authentication, VPN and management controls appropriate to the OT environment.
Are the MAXON 5G bands confirmed for every region?
No universal regional compatibility should be assumed. Request the exact cellular-module and band table, carrier status and market approvals for the chosen model.
Request a cellular design review
Send MAXON the hazardous-area classification, country, network diagram, interfaces, operator, bands, SIM policy, traffic profile and security requirements at This email address is being protected from spambots. You need JavaScript enabled to view it..