So, you need to monitor the levels of several tanks from a remote point. What is the best way to do this, and where should you begin? For many situations, daisy chaining the sensors—for example, in an RS485 Modbus network—is a simple, reliable, accurate, and cost effective way to simultaneously monitor the levels in several tanks. The best way to get started is by following a few basic installation practices.
We’ve said this several times in different ways over the past couple months: make sure your sensors make sense for your application. This applies to your communication system as well. You can use the very best installation practices, but if your sensors or communication system aren’t right for the job, none of it will matter. So, before you buy anything, make sure you have accounted for:
Remember that no matter what technology you are using to support your remote access (TCP/IP over Ethernet or internet, cellular, satellite, RF, or wired communications), your sensor signals must be compatible, or you won’t be able to monitor anything.
Since we’re primarily interested in the daisy chain installation, we’ll assume that the physical installation of your sensors was a walk in the park. No problems at all. Wasn’t that easy?
Right. Now to the fun part: wiring your sensors. Daisy chain wiring has several advantages over individual home run wiring: less cable, shorter runs, doesn’t require larger sizes of conduit. But that doesn’t mean daisy chain installation is mindless. Good wiring practices still apply.
“Dear Lightning: Please stay away from this installation. Kind Regards, Every Maintenance Crew Everywhere.”
Since lightning has yet to prove it can read, an open letter is probably not enough to protect your installation. So what can you do? If your tanks, sensors, wiring, etc. are all installed inside a building, and that building is appropriately protected, then everything should be good. But if the installation is completely open to the elements, make sure the structure of each tank is adequately protected. Also, ask the manufacturer of your sensor is it has built-in lightning protection.
Once everything is correctly installed, it’s time to power up your system. Be sure to follow any instructions about sequential instrument addition to your communication system. For example, Modbus-RTU systems require that each device be added to the system one at a time to prevent device address confusion. Being aware of little details like this before you start will greatly increase the likelihood of a successful installation.
Have questions about an upcoming installation? Having difficulties troubleshooting an existing installation? Give our helpful Measurement Experts a call, shoot us an email, or even live chat with us. Whether your signals are crossed or your sensors are incensed, we can help you get hooked up and powered up right.
top image credit: MrClementi via flickr cc
bottom image credit: Citynoise via Wikimedia Commons cc
