Fluid Detector False Positives
My fluid sensor keeps reporting a false positive. How do I troubleshoot it?
First, you should verify that the tag data arriving at the reader is being interpreted correctly by the software. See article “Troubleshooting Tag to Reader Communication”. For that procedure, note that the payload value for a dry sensor is 480; and the payload value for a wet sensor is 481.
Second, remove the film from the tag, and thoroughly inspect it. Examine the film where it connects, to ensure there are no tears in the film, and that it seats properly. There should be a 1” allowance for the end of the sensor that attaches to the tag. The other end of the film should be cut between the black dotted lines, and between the holes in the film, and should be cut very cleanly at a straight 90⁰ angle.
Clean the film with a little bit of isopropyl alcohol 99% and a lint-free cloth. Check the connector on the tag, to ensure that there is no residual water that needs to be cleaned. With the film detached from the tag, our software should report that the tag is dry. On the tag where the film connects, there are 4 pins. Connecting the 2 middle pins with a piece of wire should cause the software to report that the tag is wet. Check that the connector pins are not bent, and that the film is aligned properly. There are some small guides on the connector to help align the film. The four lines on the film need to be aligned with four rows of pins in the connector. Be sure that the side of the film marked ‘bottom’ is properly placed; the bottom has metal strips, while the top has the holes. It is very important to ensure that the bottom side of the sensor film matches up with the bottom side of the connector.
Once the film is installed, check it for bubbles, kinks, and wrinkles. A damp fingertip placed over the holes in the film, should cause the software to report that the tag is wet. Ensure that the surface to which the tag is adhered is not conductive. In some instances, conductive paint on concrete or moisture seeping up through a slab could cause problems. If you have a known-good tag and film strip available, try swapping those in to verify that there is not an environmental problem.