danstips
Blogging team for Dan's Tips, the education and tech tips blog for Lesman Instrument Company
Homepage: http://danstips.wordpress.com
HART communications without busting the budget
Posted in Communications, configuration, cost issues, HART, Level technology, service, siemens, software, transmitters on March 15, 2013
The HART communication protocol has been firmly established as the standard means of configuring field instruments for some years. But talking to a field instrument needs a communicator.
There are the handheld communicators, Rosemount’s x75s and the “budget-priced” Meriam MFC 4150, but at a cost that’s more a capital appropriation than an MRO expense. Even the Meriam, with a 3-year field device description subscription starts at more than $4000.
People continue to ask me if there isn’t a more budget conscious approach to HART configuration.
Comparing Honeywell smart transmitters
Posted in honeywell, Measurement, Pressure transmitters, pressure transmitters, transmitters, Uncategorized on February 12, 2013
Honeywell’s new SmartLine ST700 and ST800 pressure transmitter lines are replacing the existing ST3000 100 and 900 series.
If you’re using ST3000 100 series transmitters, you’ll be looking at the ST800 for future units. If you’re using the ST3000 900 series, the ST700 will be your better fit.
Siemens SIMATIC PDM programming tricks
Posted in configuration, installation, siemens, SIMATIC PDM, transmitters, Troubleshooting on January 25, 2013
When you’re making programming changes to a field device, you don’t always have time to wait. Here’s a hidden feature that helps you speed up the process between Siemens SIMATIC PDM and HART field instruments.
Normally, when you’re using PDM software, it takes a minute or so to upload or download changes to and from your HART devices. Seems like an eternity when all you need to do is change a range.
So, I’m going to let you in on a feature you might not have seen before.
How do I get an RTD signal to two different devices?
Posted in API, Communications, honeywell, installation, Loop controllers, Measurement, Modbus, precision digital, Recorders, RTDs, siemens, temperature, temperature transmitters, temperature transmitters, transmitters on November 28, 2012
RTDs are great temperature sensors – accurate and easy to install. But they are not friendly when it comes to trying to get a single RTD to go to two places, like when an RTD temperature measurement has to go to both a controller and a recorder. People call and ask, “How do I split an RTD signal?” The short answer is, “You can’t.”
An RTD cannot be wired in parallel or in series to a second device. Any RTD input supplies a known, regulated ‘excitation’ current to the RTD. Mixing RTD inputs would mix currents and that’s a Big No-No.
There’s also a lead wire compensation circuit for 3- or 4-wire RTDs that would create problems if a single RTD were connected to two different RTD inputs. There’s just no feasible means of making two RTD analog inputs play nice together.
But all is not lost. There are several ways to achieve your goal.
