TWO INPUT RANGES
Our OEM customer, who manufactures level control systems, wanted to be able to interface more than one type of level sensor with his system. Specifically, he needed to translate both 4/20mA and 0/5 volt level signals to match his system's input.
Our solution - a modified version of our JH4300 DC Input Transmitter capable of accepting both ranges. For 4/20mA the input is connected to pins 5 & 6. For 0/5 volts pins 4 & 6 are used, plus a jumper between two terminals. This avoids the need to stock two different types of signal conditioners.
More detail. Their level system normally uses a variable resistance level sensor. (In fact, they are a regular customer for our resistance input transmitters.) 4/20mA or 0/5V is only occasionally required, so they did not wish to redesign the system's electronics. Their original request was, could we translate 4/20mA or 0/5 volts to a 0/90 ohm resistance? The answer was no, this would not be a simple modification.
Instead, they determined and we verified that their electronics passes a constant 2.5 mAdc current through the sensor. Thus, 0/90 ohms translates to 0/0.225 volts. We set up our output for this range.
Conclusion: they now are able to work with several types of level sensors without modifying their system. All they need to do is connect the level sensor to our module and connect the JH4300's output to their system's input.
If you have similar needs, please remember that we can make "simple" modifications without large engineering costs or minimum order requirements. To contact us e-mail email@example.com or phone (800) 808-0300 (outside the US, 941-927-0300).
Links: Custom & Special Process Transmitters
JH Technology Web Site: http://www.jhtechnology.com/