Team, There is a project with PMI to track cigarette filter trays in the production facility. The plastic trays are equipped with Omni-ID tags. Each time an empty tray comes to the machine its tag is programmed with filter type ID. Then the tray is filled with filters and goes along the production line. When the tray gets empty (all filters are used) it returns to the machine to be refilled with filters of the same or another type so the tag is reporogrammed again - and so on. The readers are XR480s and antennas used are AN720. The distance between antenna and tag is very small - 2-3 cm at most, the distance between trays (tags) in a queue is ~10 cm. Reads are fine, writes are not. The application reads the tag after programming to make sure it's OK but in 3-7% of cases the tag disappears from the visible population after programming. The application does not return any errors when writing. The programming happens when the tray is waiting to be filled so it does not move and speed is not an issue. Read power is set to minimum, write power is ~50%, setting it lower increases the failure rate. There is a lot of metal and electricity around so there is some interference for sure but there is not much we can do about it. Questions: 1. Are there limitations on the minimal write distance? 2. Is it healthy for a tag being often programmed on such a close distance? 3. Any experience on close distance UHF applications - specific antennas/tags for this purpose? 4. What toubleshooting/programming technique can be used to help isolate the issue? Thanks Valery