ATOP MB5908-CT Rugged Serial to Ethernet Modbus Gateway
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The ATOP MB5908-CT is an 8-port rack-mount Modbus concentrator. It polls Modbus RTU/ASCII slaves on eight RS-232/422/485 ports automatically and mirrors their data into internal memory, so Modbus TCP masters on its two 10/100BASE-T(X) ports get immediate replies. It runs from -20°C to +70°C on 24-48 VDC or 100-240 VAC and suits control rooms and switchrooms with many serial devices.
Concentrator Serial Ports8 × RS-232/422/485 (RJ45), polled automatically into internal memory
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Description
The ATOP MB5908-CT is an eight-port industrial secure Modbus gateway that bridges serial field devices to Ethernet networks. It translates between Modbus TCP on the network side and Modbus RTU or ASCII on eight independent serial ports, letting PLCs, meters, RTUs and other RS-232/485 equipment share data across a modern IP infrastructure. RJ45 connectors and a rack-mount chassis suit control rooms, substations and utility cabinets, while optional serial-port isolation protects against ground loops and surges on long cable runs. Built-in security features harden the gateway for exposed OT networks. It is a practical choice when you need to consolidate many legacy serial slaves onto one supervised, secure Modbus link. See our rugged serial and Modbus gateways.
Manufacturer datasheet (PDF)
MB5908-CT specifications
| Modbus Function | Modbus concentrator (advanced tier): automatic polling of serial slaves into internal memory; Modbus TCP/RTU/ASCII gateway |
|---|---|
| Serial Ports | 8 × RS-232/RS-422/RS-485, full function |
| Serial Interface | RJ45 connectors |
| Serial Isolation | 2.5 kV (optional) |
| RJ45 Ports | 2 × 10/100BASE-T(X) |
| Redundancy Protocols | RSTP on 2 redundant Ethernet ports |
| Protocols | Modbus TCP, Modbus RTU, Modbus ASCII |
| Concentrator Features | Customisable register mapping, link status and data timestamp access, exception error handling |
| Modbus Redundancy | Redundancy option listed |
| Modbus Function Codes | 1, 2, 3, 4, 5, 6, 15, 16, plus 43 Read Device Identification (server side only), per ATOP's Modbus protocol specification |
| VPN | Supported |
| Relay Output | 1 |
| Input Voltage | 24-48 VDC; 100-240 VAC |
| Mounting | 19-inch rack-mount |
| Ingress Protection | IP30 |
| Dimensions | 440 × 44 × 200 mm (L × H × D) |
| Operating Temperature | -20°C to +70°C |
| Storage Temperature | -40°C to +85°C |
| Certifications | CE/FCC, EN 60950-1 and/or EN 62368, industrial EMC protection |
Specifications taken from the manufacturer datasheet.
Which version do I need?
This page covers the MB5908-CT, the concentrator build of ATOP's 8-port rack-mount platform. The selection guide's MB5908 row covers both the MB5908 gateway, which translates Modbus TCP to RTU/ASCII and suits periodic polling, and the concentrator function sold as MB5908-CT. The MB5908A-CT is the substation version: six Ethernet ports, IEC 61850-3, DSub9 or terminal-block serial connectors with 3 kV optional isolation, redundant power inputs and -40°C to +85°C operation. Choose the MB5908-CT for control rooms within -20°C to +70°C.
Typical applications for the MB5908-CT
- Concentrating Modbus RTU meters and relays in a switchroom for a Modbus TCP SCADA
- Serving a SCADA and an engineering workstation from one set of serial slaves with different register maps
- Avoiding Modbus TCP timeouts when many slow serial devices share one link
- Building and plant energy monitoring with frequent polling
- 19-inch racks in control rooms and utility cabinets
Complete the stack
Products that work with this one — connect it, power it, and get it online.
MB5908-CT — frequently asked questions
What does the -CT concentrator add over a plain Modbus gateway?
A plain gateway translates each Modbus TCP request into a Modbus RTU/ASCII request on the serial line, which ATOP rates as suited to periodic polling. The -CT concentrator polls the serial slaves automatically with pre-defined commands and mirrors their data into internal memory, so Modbus TCP masters are answered at once without risk of timeouts; it adds customisable register mapping for masters that need different data structures, plus link status and data timestamp access.
How many ports does the MB5908-CT have?
Eight RS-232/422/485 serial ports on RJ45 connectors and two 10/100BASE-T(X) Ethernet ports with RSTP redundancy, plus one relay output.
What power supply does it need?
ATOP lists 24-48 VDC and 100-240 VAC power inputs for this model. Power redundancy is not listed for the MB5908; the MB5908A-CT has redundant power inputs.
What temperature range is it rated for?
-20°C to +70°C operating and -40°C to +85°C storage, in an IP30 rack-mount housing of 440 × 44 × 200 mm.
Is serial isolation available?
Yes, 2.5 kV serial isolation is an ordering option on the RJ45 serial ports.
What is the difference between the MB5908-CT and the MB5908A-CT?
Both are 8-port concentrators. The MB5908A-CT adds IEC 61850-3 certification, six Ethernet ports instead of two, DSub9 or terminal-block serial connectors with 3 kV optional isolation, a 100-370 VDC input option, redundant power and a -40°C to +85°C rating.
How much does the ATOP MB5908-CT Rugged Serial to Ethernet Modbus Gateway cost in the UK?
The ATOP MB5908-CT Rugged Serial to Ethernet Modbus Gateway is supplied to order and priced on application. Send a quote request and we confirm the price and lead time in writing, usually the same working day. No account is needed. Indiott is a UK distributor invoicing with VAT (PSI Technologies Ltd, VAT GB 730 2340 83).
What is the lead time and delivery cost for the ATOP MB5908-CT Rugged Serial to Ethernet Modbus Gateway?
The ATOP MB5908-CT Rugged Serial to Ethernet Modbus Gateway is supplied to order. We confirm the lead time in writing with your quote, before you commit to anything. UK delivery is a flat £14.25 per order ex VAT, whatever the weight or how many items you order. We ship to GB and the EU and provide a VAT invoice with every order.
