Modbus Concentrator

Industrial High-Performance Modbus TCP/RTU/ASCII Gateways with Concentrator function and Advanced Redundancy Features.

  • With only one connection/one query, master device will be able to access all connected IEDs’ data through the ATOP Modbus concentrators
  • Database synchronization for redundancy when two concentrators work in pair
  • 4 or 8 or 16-port RS-232/422/485, baud rate up to 921.6 Kbps ? Isolated redundant power inputs with 24-48 VDC ,100-240 VAC variations
  • Works in environments from -40 to 70°C or -40 to 85°C
  • IEC 61850-3 and IEEE 1613 Power Substation Standards certified ( Only IEC61850-3 models)


ATOP Modbus concentrators are interpreter with powerful concentrator features between Modbus over Serial Line devices and computer hosts running Modbus/TCP on Ethernet networks. Fully compliant with Modbus/TCP protocol, this device offers a convenient solution to connect existing devices or controllers running Modbus serial protocol (Modbus/ASCII or Modbus/RTU) to an Ethernet network. ATOP Modbus concentrators are standard Modbus gateways that convert packets between Modbus TCP and Modbus RTU/ASCII protocols and they can work in 3 different modes:


  • Gateway mode (simple translation from Modbus TCP to Modbus RTU/ASCII)
  • Concentrator mode (enhanced performance)
  • Concentrator/Redundant mode (two coupled devices guarantee maximum performance and faultproof solution)


The device supports 16 simultaneous TCP masters and 32 simultaneous requests for each TCP master. Each RS-232/422/485 serial port can be individually configured for Modbus/RTU or Modbus/ASCII operation with different baud rate, allowing both types of networks to be fully integrated with Modbus/TCP within one package. When the concentrator function is enabled, with only one connection/one query, master devices will be able to receive all connected IEDs’ data from ATOP Modbus concentrator Series. When the redundancy function is enabled, all connected devices still remain reachable even in a network breakdown event, unless more than one connection line is compromised.

Modbus Gateway Feature

As a Gateway, ATOP Modbus concentrator will translate Modbus/TCP frames from the Ethernet network into Modbus RTU/ASCII requests through RS485-RS422-RS232 serial line transparently and relay the response to the master.

Redundancy Feature

As an ultimate feature, ATOP Modbus concentrator Series supports redundancy. Unlike other regular concentrators in the market, an interconnected pair of Modbus Concentrators, can easily be set up to form a solid, redundant backup network preventing cable, network or device breakdown into mission-critical applications. Assuming IEDs are connected in a RS-485 chain from one concentrator to another (see picture below), shall a serial line fail to poll an IED, the secondary gateway will try to poll it and –if successful- relay the data back to the primary device. This will also be able to relay, with predefined registers, the information back to the Master. In this example, Master A can still reach IED 1 through the secondary network when the primary network is down. No data will be missing while technicians repair the primary network. Otherwise, if it’s either the Ethernet link or one or the other concentrator to be down for any reason, the concentrator still running and connected to the network will take over the polling Job reporting data, timestamps and link failure information to the Master.