Fieldbus Beginner

[dave]

:confused: Hi, I have a Fisher DVC6030f positoner w/valve actuator, a HART 375 Field Communicator and a 24vdc power supply. My question is, Do I need any other hardware to be able to communicate to the positioner, perform autotuning and then manually stroke the valve actuator using the communicator?
I have limited experience with the Fisher positioners and zero experience with Fieldbus. Any help would be greatly appreciated!

[jcpilman]

The 375 has two communications modes: HART and Foundation Fieldbus. Be sure your license and software includes the Foundation Fieldbus functions and use the web based software to update your Foundation Fieldbus DD files.

To connect the 375 to the positioner, you need a fieldbus power supply or power conditioner. A well regulated 24 VDC supply will not work because the regulator will interfere with the modulated communications on the line. You should also use two terminators, even on a short segment.

You will not need any other Link Master or Link Active Scheduler
on the bus to perform the activities you described.

[mikestrauser]

Dave,

We make a product just for your situation. It is a benchtop power conditioner that comes with a Wall Transformer. Two terminators are built into the unit and there are connection points for 4 devices. It is called a Power Hub. Please see our website (link below) for more information.

Mike.

[jcpilman]

I have used the Relcom Power Hub and the Relcom IPM. They both work well and the Power Hub simplifies workbech connections, but I recommend the IPM because of its superior short circuit protection. The IPM comes on a base such as the FPS-DT. The FPS-DT requires a DC power supply. It provides one terminator, so another is needed.

[mikestrauser]

I would not hesitate to use the Relcom Power Hub for bench testing. Last year we made improvements to the unit to make it more robust when subjected to a long term short circuit.

[jcpilman]

Thanks for the update Mike. In that case I would also go with the power hub. I think that improvement would be worth including on the Relcom website.