mybrew / Modbus-Master

Modbus master library for LabVIEW

Plasmionique Modbus Master

Copyright © 2016, Plasmionique Inc. All rights reserved.

Author: Ryan Porter LAVA Name: Porter Contact Info: Contact Porter via PM on lavag.org

LabVIEW Versions: LV >=2012 (Windows)

Dependencies:

• None

Description:

This package contains an open source Modbus master library for LabVIEW. This has been developed as a replacement for NI Modbus V1.2.1 and provide an open source alternative to the NI Modbus Community API.

It supports RTU, ASCII and TCP modes with the following function codes:

• 0x01 - Read Coils
• 0x02 - Read Discrete Inputs
• 0x03 - Read Holding Registers
• 0x04 - Read Input Registers
• 0x05 - Write Single Coil
• 0x06 - Write Single Register
• 0x07 - Read Exception Status
• 0x0F - Write Multiple Coils
• 0x10 - Write Multiple Registers
• 0x16 - Mask Write Register
• 0x17 - Read/Write Multiple Registers
• 0x2B/0x0E - Read Device Identification

Supports sharing a serial port across multiple Modbus sessions using VISA locks (10 second timeout). Supports sharing a Modbus session across multiple communication loops using a DVR as a mutex.

Installation and instructions:

• Install VIP package using VI Package Manager.

Examples:

• "(LabVIEW)\examples\Plasmionique\MB Master\MB_Master Comm Tester.vi" Demonstrates usage of API to open/close connection and communicate with a Modbus slave device.
• "(LabVIEW)\examples\Plasmionique\MB Master\MB_Master Multiple Sessions.vi" Run multiple Modbus sessions on either shared or separate comm ports/IP addresses.

Documentation:

• "(LabVIEW)\help\Plasmionique\MB_Master - User Guide.pdf"

Known Issues:

• Only MEI type 14 is properly supported in RTU mode.

Acknowledgements:

• Thanks to LAVA users smithd, bbean, and Mark Balla for taking to time to review and comment on the code.

Version History:

• v1.0.0: Initial release.
• v1.0.1: Converted PDU class to cluster
  • Removed inter-frame wait time optimization. It may have caused problems with shared serial ports
  • Renamed NumBytes of PDU to RTU_DataBytes
  • Made build and interpret Vis of PDU private
  • Removed function Vis from MB_Master class
  • Removed PDU_req and PDU_resp from the MB_ADU class
• v1.0.2: Added accessor for VISA resource to MB_Master_Serial class. Allows tweeking of VISA settings after Open Serial Session has been called.
• v1.0.3: Added dynamic dispatch accessors for ADU and Session Valid to MB_Master class.
  • Combined "MB_Master Serial Comm Tester" and "MB_Master TCP Comm Tester" in to one example "MB_Master Comm Tester.vi"
  • Combined "MB_Master Serial Multiple Sessions" and "MB_Master TCP Multiple Sessions" into one example "MB_Master Multiple Sessions.vi"
  • Removed Shared Session examples.
• v1.0.4: Added dynamic dispatch accessor for Slave ID to MB_Master class.
  • Changed type of RTU_DataBytes in MB_PDU_Cluster from U32 to I32
  • Modified RX ADU.vi of MB_ADU_RTU class in order to have RTU support for function codes of unpredictable data length (24, 17, 12, 20, 21, 43).
• v1.0.5: In RX ADU.vi of MB_ADU_RTU class:
  • Fixed the conversion of byte count.
  • Added special case for Function code 24 read FIFO queue (byte count is 2 bytes long!).
  • Fixed CRC check for other MEI types.
• v1.1.0: Added user manual.
• v1.2.0: Re-mapped error codes to range (403460, 403499)
• v1.2.1: Re-worked VISA locking behavior for MB_Master_Serial
  • Added new library MB_VISA_Lock which is a wrapper for VISA Lock
  • Added 10ms delay between retries of serial transactions
  • Removed accessors for VISA resource in MB_Master_Serial
• v1.3.1: Re-Added accessor for VISA resource. Some might find this useful for dealing with certain USB to serial adapters.
  • Added Modbus Comm Tester to tools menu.
  • Added MB VISA lock functions to palette.
• v1.3.2: Added support for transaction IDs to TCP mode.
  • ADU contains PDU request and PDU response, which are available via property nodes.
  • Added device ID objects to Modbus Comm Tester
• v1.3.3: Fixed session valid property of MB Master TCP class
• v1.3.4: Updated documentation
• v1.3.5: Improved RTU CRC calculation speed.

License:

Distributed under the BSD 2-Clause (http://opensource.org/licenses/BSD-2-Clause) See link for a full description of the license.

Support:

If you have any problems with this library or want to suggest changes contact Porter via PM on lavag.org or post your comment on the support forum: https://lavag.org/topic/19544-cr-plasmionique-modbus-master/

The development source code is available on GitHub: https://github.com/rfporter/Modbus-Master

References:

1. Modbus Application Protocol: http://www.modbus.org/docs/Modbus_Application_Protocol_V1_1b3.pdf
2. Modbus Over Serial Line: http://www.modbus.org/docs/Modbus_over_serial_line_V1_02.pdf
3. Modbus Messaging on TCP/IP: http://www.modbus.org/docs/Modbus_Messaging_Implementation_Guide_V1_0b.pdf
4. NI Modbus Library: http://www.ni.com/example/29756/en/
5. NI Modbus Community API: https://decibel.ni.com/content/docs/DOC-30140