TCP Communication Library

OpenVMS™ Modbus/TCP Communication Library©

The IPACT Modbus/TCP Communication Library© provides an Application Programming Interface (API) for user written application processes on HP’s OpenVMS systems (Alpha or Itanium).

The IPACT Modbus/TCP Communication Library allows connectivity to the Modbus Devices capable of modbus TCP/IP over ethernet.  The OpenVMS host is modeled as both a PLC and as a message oriented device.  The following services are provided for OpenVMS application processes:

• Read Input Discretes from a programmable controller
• Force a single coil in a programmable controller
• Preset a single holding register in a programmable controller
• Read or write the extended memory files in a programmable controller
• Read or write one or more holding registers
• Read or write one of more coils in a programmable controller
• Read programmable controller exception status
• Read/write a register or set of registers as a single operation in a programmable controller
• Mask write a single register in a programmable controller
• Read FIFO queue from a programmable controller
• Virtual Modicon PLC served by OpenVMS host
• Support for Modbus Plus Slave paths (Remote Master read or write to a VMS host):

1. Write slave path messages to a VMS Mailbox
2. Suspend and resume the accepting of slave path messages from remote Modbus Plus masters
3. Read or write OpenVMS holding registers modeled in process memory
4. Read Modbus Plus Network unsolicited messages from the OpenVMS mailbox

The API calls are provided in both synchronous and asynchronous versions.   All calls to the API use the same numbering convention as the Modicon PLCs (e.g. the first holding register is 40001).  The library is provided as a sharable image and as a linkable object library.

Documentation

If you like, you can download a copy of the documentation.  The documentation is an Adobe Acrobat (.PDF) file.

Applications

Ordering Information

IPACT Modbus Plus Communication Library for OpenVMS:  $2900.00US dollars per node.  For more information regarding this or other IPACT products, contact us directly.

Integrated Process Automation & Control Technologies