Modbus Serial

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Product Overview

The Modbus Serial device driver provides data exchange between OPC clients and Modbus Serial protocol compliant PLCs and other devices. Kepware automatically optimizes your data acquisition based on client demand. Data integrity is ensured with our extensive error handling.

Special handling has been added to support the native memory formats of the OMNI Flow Computer including string support. Additional configuration parameters allow this driver to tailored to a wide range of Modbus Serial compatible devices, including JBUS.

The Modbus Serial driver now offers direct integration with Modicon Concept and ProWORX programming packages. If you are using either of these packages, you will be able to import the tags used in your PLC application directly into Kepware. This time-saving step instantly makes all of the relevant PLC data available to your OPC client applications.

  • Ethernet Encapsulation
  • Supports the TSXCUSBMBP USB adapter for the Modbus Plus Network
  • Modbus RTU Multi-drop Supported
  • Automatic Tag Generation
  • Supports Broadcast Messages using device ID 0
  • Full Address Range Support (0 - 65535)
  • Hex Addressing Support (0-FFFF)
  • User Definable Read Block Sizes
  • Adjustable Address Base (0 or 1)
  • Word Order Swapping for Floating Point and Longs
  • Byte Order Swapping on all 16 bit and 32 bit values
  • Adjustable RTS Flow timing for Radio Modems
  • Supports all memory types and data types
  • Support accessing Holding register memory as string data with HiLo/LoHi byte order
  • RTU Functions used: 01, 02, 03,04, 05, 06, 16
  • Supports tag import from Concept and ProWORX programming packages
  • Modem Support
    • Automatic Dial Configuration
    • Multiple Phone Number Management
  • Communication Serialization
  • Modbus RTU Protocol
  • Daniel S500 Flow Computer
  • Dynamic Fluid Meter
  • Elliot Flow Computer
  • Magnetek GPD 515 Drive
  • Modbus Compatible Devices
  • Omni Flow Computer (Enron Modbus)
  • English
  • German
  • Japanese
  • Simplified Chinese


  • Fixed an issue timing out when the PLC connects, but refuses the request.



  • Fixed an issue where a write failure could cause communication for that tag to stop.
  • Fixed an issue where System._FailedConnection tags could report incorrect values.



  • Fixed an issue where the Request Timeout was incorrectly used instead of the Connect Timeout when the driver was not connected.



  • Added support for monthly report generation for the Omni model.



  • Expanded the Connect Attempts feature introduced for Ethernet Encapsulation in the 6.6.348.0 release to honor the connection timeout when not connected.


  • Added a Connect Attempts setting to specify the maximum number of tries. The new setting is in the Timing group of device properties available when the connection type is Ethernet Encapsulation.



  • Added Chinese language support.



  • Removed redundant default setting from the Daniel S500 model.
  • Fixed an issue where array length was converted to hex when the address is specified as hex.
  • Increased the channel limit from 256 to 2048.



  • Removed hard-coding of FirstWordLow setting for DanielS500 devices.
  • Increased channel limit from 256 to 2048.



  • Added German language support.
  • Added Japanese language support.


  • Changed formatting of array length to always be decimal when the address is specified as hex.
  • Removed the hard coding of m_bFirstWordLow for Daniel S500 devices.


  • Fixed an issue where the ""First Word Low” setting under the Data Encoding device property for Daniel S500 model was always enabled.
  • Fixed an issue introduced in the 5.19 release where the decimal array length was converted to hexadecimal if the address format was specified as hexadecimal.



  • Added support for padding addresses for both 5 digit and 4 digit format. If 5 digits or more are used, the address entered is padded to 5 digits (400001). If 4 digits or fewer are used, the address entered is padded to 4 digits (40001). This applies to all model selections except Omni and Daniel S500.



  • Enhanced the driver to support Advanced Statistics tags, including ""_CommFailures"" and ""_ErrorResponses"".
  • Fixed an issue where switching models did not update controls availability.



  • Updated the driver with the new Connection Sharing feature.
  • Fixed an issue where the RTS Delay and Inter-Request Delay settings were not respected during the write portion of a Read/Modify/Write transaction.
  • Fixed an issue where write tags were orphaned if extra bytes were received in the response to the read portion of a Read/Modify/Write transaction.

    Note: A Read/Modify/Write transaction occurs when writing to a bit within a register if ""Holding Register Bit Mask Writes"" is not used.



  • Increased the character limit of the tag Description field from 64 to 255.
  • Added the new device-level internal tag "_FailedConnection" that indicates the driver failed on its attempt to connect to the device.


Added support for Channel Serialization.


  • Fixed a potential heap corruption issue (when an expandable buffer was being overwritten) by reading an Omni Custom Packet Tag. A maximum size of 250 bytes was assigned for an Omni Custom Packet Tag instead of allowing the tag data type to determine the buffer allocation size.


  • Increased the number of channels from 100 to 256.


  • Fixed issue with write-only tags introduced in 5.0. The value of the tag was not updating when a value was written to it. The correct value was written to the device, just not displayed in the data client.


  • Added string data type support for Internal Registers.
  • Added block string read support.