Modbus

Connect to Modbus TCP devices

The Modbus TCP feature of the Cogent DataHub provides real-time data exchange between the Cogent DataHub and any Modbus TCP/Ethernet compliant PLC or device. The feature is available in three DataHub products, the DataHub Modbus OPC Server, DataHub Modbus Tunneller, and the DataHub Modbus Logger.

When combined with other DataHub features, each of these products provides the ability to fully utilize data from multiple Modbus devices, for example:

Mobus screen capture

Features of the DataHub Modbus Driver

The following Modbus features are supported:

  • Unlimited connections to slave devices
  • Automatic connection re-try with configurable delay
  • Automatic message size optimization
  • User-configurable options on a per-slave basis
    • Host name / IP address and port
    • Automatic IPV6 connection with fallback to IPV4
    • Polling rates from 10 ms
    • Optional use of Modbus functions 5, 6, 15, 16 and 22
    • Maximum message length from 20 to 260 bytes
    • Zero- or one-based addressing
    • Zero- or one-based bit addressing within registers
    • MSB or LSB bit order within registers
  • Flexible data point configuration:
    • 16, 32 or 64-bit signed and unsigned integer input and output
    • 32- and 64-bit floating point input and output in any byte order
    • ASCII, UTF-8 and UTF-16 strings
    • Range specification to configure many consecutive points at once
    • Bit-field addressing within registers, including multi-bit fields up to 64 bits in length
    • Bit range specification to configure many consecutive bits within a register at once
    • Read-only mode for addresses in output data blocks
    • Automatic next-in-sequence point configuration
    • Arrays of digital and analog types
    • Deadband for analog types
    • Linear transformations with clamping
    • Type conversion
    • Addresses up to 65535

These products support Modbus:

Product Code Features
DataHub Modbus UA Server DHMBUA OPC UA, Modbus
DataHub Modbus DA Server DHMB OPC DA, Modbus
DataHub Modbus Tunneller DHMTUN Modbus, Tunnel/Mirror
DataHub Modbus Logger DHMBLOG Modbus, Database
Modbus TCP support ** ADDMB Modbus

* Includes Aggregation, Scripting, QuickTrend, and Security
** Available as an add-on feature