Why can't I receive data when the PLC says my HI 3000 series unit is online?

Using a Hardy 3000 series (HI 3010, HI 3030, HI 3300 or HI 3600) with Control Net, why can't I receive data when the PLC says my Hardy Instrument is online?  All values received are "0", but the controller has good readings in all channels.

If your PLC indicates that your HI 3000 series Hardy Instrument is online but you are not receiving any data, you are probably either missing or have incorrect mapping in your Hardy Instrument.

Try deleting and re-entering the mapping in the unit.

If you have multiple units and another unit is working correctly, try swapping the node address between the two units and see if you have a problem with a particular address, or if it is this particular location. If the problem follows this location, it may be a mapping issue or a bad unit. If the problem follows the address, then it is a programming issue in the PLC.