INTRODUCTION

The Low Tape warning is an important function of the BP-PLC LTNT (Low Tape No Tape) system. It provides advance warning to the operator that the roll of tape is getting low and should be replaced soon. The Low Tape warning is a not fault; The machine will continue to function normally in a low tape state. If your machine is faulted, then the Tape Monitoring function is to blame. This article specifically addresses troubleshooting as related to the LOW Tape warning.

OPERATION

When low tape is detected, the amber light on the stack will cycle on and off at a 1 second interval.  The low tape condition is only checked when a box exits, after tape is dispensed, so the Amber light may continue to flash after a new roll is loaded. The next box through the machine will update the low tape status and shut the Amber Light off.

OBSERVATION

There are two sensors mounted next to the tape head. The sensor on the short bracket is for No-Tape Faults. The sensor on the longer bracket aimed at the roll is for Low Tape Warning.

 
The photo eyes have two adjustments: sensitivity and Light/Dark mode. Sensitivity dial adjusts the range of detection. The dial has about 270 degrees of rotation- Min to Max. The Light/Dark (L/D) mode sets the output state of the sensor when it detects an object; it has about 90 degrees of rotation.

Tape Fault (No-Tape/No-Cut) Monitoring and Low Tape Warning are two separate functions and can operate independently of each. Nuisance tape faults, caused by a bad No-Tape Sensor, can be disabled, but the status of the roll can still be monitored. For top/bottom seal only, the tape head can be removed, tape monitor disabled and the sensor state changed.
The Low tape sensor should be set to 'D' (Dark-ON mode) for detection...

 
... or 'L' (Light-ON Mode) if the tape head is not loaded.   

When the sensor is set to Dark-On, the output only turns 'ON' (amber LED will illuminate on the sensor) when the sensor clears because of 'Low Tape'. When set to Light-ON, the sensor output should never turn 'ON' because there is no tape head or tape roll to detect.