This error message indicates that the Process Variable is below the lower limit of the range. For example, if the temperature is -5C when the range is set for 0 to 300C. The 3 digit display as used on the model 6500 will show [L].
This error can be caused by wiring the sensor backwards.
This message can also be generated if the input is incorrectly wired, or the input code and/or jumper are not correctly set for the type of signal applied.
Check the following sections in your product manual to correct these conditions:
Connections and Wiring
Internal Links and Switches
Configuration Mode - Input Code