Many Distributed Control Systems (DCS) that were created in the 1970s and 1980s were developed with proprietary hardware and software.

These Distributed Control Systems were very robust, and many are continuing to operate until this day. One of those would be the Honeywell TDC 3000 system.

I have no idea how many are still operating equipment across the world today as they have for the last 30+ years and many companies are hesitant to upgrade because they have such high reliability.

Honeywell has now been producing their Experion line of Controllers for a couple of decades and they are a completely different line of controller that is configured from a more open platform using Microsoft Windows.

Honeywell has done a great job of maintaining legacy hardware when upgrading from the TDC system to an Experion System. I believe the current support for TDC 3000 I/O (PM I/O) is out to at least 2035, so it is not going anywhere for a while.

If you wish to convert a system from a PM (Process Manager) or HPM (High Performance Process Manager) to an Experion Controller, you can essentially remove the HPM controller, Install a C300 Controller and make the PM I/O a part of the Experion System.

This is the basics of how to add PM I/O to an Experion Controller and it would be done during a planned system downtime.

Hardware Configuration

1) As part of the C300 “Violet” I/O Link, you will need a pair of redundant I/O Link extenders to extend the I/O Link via fiber to the PMI/O Cabinet:

2) Remove the PM or HPM and the ComCtl module.

3) Add a PM I/O Extender and I/O Link Coupler to the PM I/O Cabinet in the same slots as the HPM and ComCtl Module was located as shown below. These redundant IO links will be in the same slots as the redundant HPMs were in, usually in separate card files:

4) Now the HPM Addressing must be removed and all the jumpers set to the UP Position for remote I/O:

Old Address

New Address

Software Configuration

1) In Control Builder, you will set the I/O Link up as a “PM_IO_TYPE” as shown below:

2) When adding your PM I/O Modules, you will give them an IOP number the same as they had in the TDC Configuration. You will also give them the File and Card number the same as in the TDC Configuration. The Tag Name can be anything meaningful to you. I added them here with the file and slot location and module type:

3) When you build a control module and wish to use a PMIO channel, you will select a block from the PMIO Library and assign it to the PMIO Module:


If you are looking to upgrade your Legacy TDC 3000 System Controllers to Experion C300 Controllers, then hopefully this will give you some insight to what that looks like from a hardware and software perspective.

The configuration differences between a TDC System and an Experion System are many as they are built on completely different platforms, however, Honeywell has done a great job to integrate their latest and greatest with the legacy systems that they still support and the PM I/O modules run reliably for many years.

Written by Brandon Cooper
Senior Controls Engineer and Freelance Writer

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Brandon Cooper