Wiring Diagram for the E-1608 connected to a Alsonic-FX2 Transit Time Ultrasonic Flowmeter that uses 4-20mA signals

[TonyT]

ALSONIC-FX2 manual 2021.pdfALSONIC-FX2 manual 2021.pdf

[JRys]

How to connect a single 4-20mA sensor to E-1608 differential input.

1. Connect Positive (+) External Power Supply connection to Positive (+) Sensor connection
2. Connect Negative (-) Sensor connection to Positive E-1608 (+) Input connection
3. Connect Negative E-1608 (-) Input connection to Negative (-) External Power Supply connection
4. adding a 250 Ohm load resistor across the Positive E-1608 (+) and Negative E-1608 (-) Input connections.  This will generate a voltage drop of between 1 and 5 Volts which is directly proportional to the 4-20mA signal.

Refer to the Alsonic user manual for External Power Supply voltage range. I believe they suggest anything between 12 and 36 volts. 

best regards,

John

[TonyT]

Do we need to a have a power supply in order for this to work because right now al sonic sensor being powered by 120 VAC not 10-36 VDC ?

Edited November 30, 2022 by TonyT

[JRys]

If the Alsonic is powered then there is an existing 4-20mA current loop. In this case, add a 250 ohm resistor to loop and measure the voltage across it with an E-1608 differential input.  Ideally, you want to resistor closer to the power supply negative not the positive to minimize common mode voltage.  Take a look at the second picture in the following article: https://kb.mccdaq.com/KnowledgebaseArticle50526.aspx

Best regards,
John

[TonyT]

2 hours ago, JRys said:

Where would I actually hook up the wires on the E-1608?

 

[JRys]

From page 12 in the user manual:

https://www.mccdaq.com/pdfs/manuals/E-1608.pdf

Connect Analog Input HI (CH0H) and Analog Input LO (CH0L) across the resistor.

[TonyT]

17 hours ago, JRys said:

 

I’m sorry but I’m having some real hard trouble with the 4-20 mA signal converting it into a 5 volts right now there’s two terminals on the Al sonic that says 4- 20 mA  plus and minus I have a 250 ohm resistor in line with the negative of the on the house sonic and I still have 20 V between positive and negative terminating to the E-1608 the drawing on the manual says I need a power supply. I have 20 volt coming out of the electrical board on the Al sonic I don’t need a power supply or do I.please help thanks 

[JRys]

Your device has two wires for 0/4-20mA current however, what is not known is if they are live or if you need to use a DC power source. Most of the 4-20mA sensors I encounter are not live and need a DC power source, but yours is more advanced. Here's a simple test, connect I+ and I- across the 250 ohm resistor. If there is current, the resistor will develop a voltage drop. **Configure the flow meter for 4-20mA and use a voltmeter to measure across the resistor. If the flow meter is registering no flow, the current will be 4mA and it will produce one volt across the resistor. ( on 4-20mA systems 4mA is zero and 20mA in maximum) If we get lucky and it is live, simply replace the voltmeter with the E-1608 CH0H & CH0L. 

If it is not live and you have 20 volts coming from +DC to -DC, wire +DC to +I, wire -I to CH0H, wire CH0L to -DC. The resistor goes across CH0H and CH0L. If the resistor is small enough you can stuff the lead and the wire into the screw terminal.

**5.6.4~20mA Current Loop Output The ALSONIC-FX2 comes with an analog current output that may be configured either as a 0–20 mA or as a 4-20 mA output. The analog output is configured in menu window M32. Within menu M32, the output 0-20/4-20 mA type may be selected, the full scale flow rate corresponding to the 20 mA output may be set, and certain predetermined milliamp outputs may be generated for testing purposes.

John