KristjanH (Customer) asked a question.
DL24-00 pulsating on 4-20 mA
We have a couple of sites where we experience trouble on Flowline DL24-00 (ultrasonic level sensor).
One of the sensors is connected to a BX-08AD-3 on a BX-DM1E-M-D and the other sensor is connected to an analog input on a BX-DM1E-36ER3-D.
The sensors are transmitting short spikes every 3 seconds, see attached log.
Is this a known issue with DL24-00? Any hints about what could be going on?
Not with a BRX (a Click Plus,) we use a 0-10V ultrasonic sensor and I had to code a math instruction to provide standard averaging to filter the spikes so readings were smoothed. Maybe you must do the same?
DF1 is my input, filtering to DF100 and the DF100 value is used for the level sensing code.
Thank you Todd. I am actually using the native filtering function on BX-08AD-3 to smooth all my analog inputs but the filtered value for the level sensor (25 cm) is incorrect. Correct value is around 130 cm.
In one of the sites we first had a sensor that was acting up all the time so we tried moving the signal to a different PLC input and when this didn't help, we replaced the sensor with a new one. The new one has been relatively stable (+95% uptime) with correct readings and no pulses for 4 weeks, but last night it went back to giving pulses that filter as the incorrect low level.
Can you isolate the circuit for testing? Dedicate a power supply to run this circuit only. Are there outputs cycling when this is occurring that you could remove? I would suspect a noise issue but the frequency of the spikes doesn't appear to be random.
I have one of the sensors in my office. Measuring the sensor stand-alone with a process calibrator, I see spikes every 6 seconds. This makes me suspect the sensors being faulty but since we have multiple sensors behaving the same (2 separate sites, both sensors replaced), I am in doubt.
There are no cycling outputs in the system.
I was hoping to find some configuration error on the sensor so I tried connecting to the sensor with WebCal configuration software through the USB-FOB but no device was found. Maybe this is indicative of a faulty device, some circuits being blown? But again - all four sensors - sounds unlikely.
If you're testing a sensor in your office, it's quite easy for it to go into fault mode, due to no liquid detected, poor signal response, probably due to angle, etc. In the real world, it sends these blips for reasons such as condensation on sensor surface, signal strength, etc.
When we configure the sensors in the office, we test the sensors by measuring the distance to a solid object. Testing with this method now is still giving me the spikes and no reliable reading.
I have now cleaned the sensor surface - still no luck.
I suggest you phone in and speak with tech support about this. I am not finding any reports of this sensor behaving as you describe but you are seeing this on multiple units.
(800) 633-0405
I did speak with tech support but we were unable to find the reason for the sensors failing.
We are using the red and black wires for the 4-20 mA signal. These wires are extended about 30 meters to the control cabinet. We actually extended all wires but only red and black are terminated, other wires are securely blinded in the cabinet (no short circuits). The level sensor manual says "... do not extend the green a white wires beyond 15'..." Is there any risk of damaging the sensor by extending the green and white wires?