Archive for category Communications
Written by: Dan Weise
I couldn’t communicate with a HART device. The configuration software I was using, Pactware, thought the USB HART modem was on COM 3, while Windows’ Device Manager showed it was actually on COM 6.
To change the COM port in Pactware to COM 6, I right clicked COM 3 and selected Parameter:
If you work in the industrial sector, you understand the never-ending push to increase uptime and improve reliability at your plant. Today’s processes require faster and more accurate engineering. Because of this, most companies are looking for ways to boost operational effectiveness and increase maintenance efficiency at their plants.
A distributed control system (DCS) is a control system where control elements are distributed throughout the system, as opposed to using a single controller at a central location. But how do you choose the right DCS? And how do you decide what functions are critical to your process?
Honeywell recently released a white paper that discusses five key features for a perfect fit DCS if you’re thinking about implementing one at your plant.
Everyone agrees that it’s good practice to keep a record of configurations and setups for any field instrument. I’m constantly recommending it to our customers for their transmitters, controllers, recorders, and other complex configurable devices.
Siemens clamp-on ultrasonic flowmeters even have a system in place to make this process easy. By connecting the meter to a PC through the RS-232 serial port, you can use a terminal program and the SITE command to fetch a data file that holds all the instrument’s configuration data.
The terminal program can also be used — with a set of instructions specific to the flowmeter — for viewing real-time operational data, performing device setup, uploading logger data, or uploading configurations known as SITE setups.
Recently, I was called to visit a plant and look at a misbehaving flowmeter. From previous discussions with the operator, I knew he’d saved SITE setup files for every flowmeter installed in the plant.
I asked if the customer would e-mail me the setup file before my visit, so I could check out how the flowmeter was set up. My request was met with a chuckle and “Well, if you really think it’s worth it…”
More and more people are using Modbus to get data from their instruments and controllers back into their control systems for reporting, alarming and troubleshooting.
And while I can’t be there to help you set up your Modbus master, I can give you 13 rules and some general practice advice for communicating to any Modbus RTU device.
It was bound to happen sooner or later.
I took a call from a customer who needed to replace a garden variety differential pressure transmitter… with one exception: He needed Honeywell’s DE digital protocol for communicating to his DCS. The DE protocol is still great, but since so many installations today use HART or Foundation Fieldbus, all of our in-stock pressure transmitters had a HART communication card – a critical mismatch to what the customer needed.
A year ago, we would have been stuck rush-ordering a unit from the factory, with all the attendant delays and expediting charges, because you couldn’t swap out a comms card without making the transmitter’s hazardous approval invalid.
What could we do?
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Before I talk about the value of a universal 4-20mA analog output on a level controller, let me explain why anyone would care. It’s all about ground loops.
Since the early days of electronic instrumentation, way back when, even before cell phones or PCs, instrument people struggled with ground loops that create an offset error, drive the signal off scale, or burn up an analog circuit.