Multi-point level indicator system

An apparatus for monitoring the level of the material in each of first and second hoppers including first and second sensor means for generating first and second pluralities of output signals respectively representing the amounts of the material in the first and second hoppers at associated levels respectively, comprising:

• means for periodically reading the output signals of each of the sensors over a predetermined time interval to generate first and second total sensor output signals representing the sums of the respective pluralities of first and second output signals read;
• means responsive to said first and second total sensor output signals for generating first and second status signals when the material in the first and second hoppers respectively is a predetermined amount at the associated level;
• and first and second indicating means responsive to said first and second status signals respectively for indicating that the material amounts in the first and second hoppers respectively are at said predetermined amounts respectively.

An apparatus for monitoring the level of material in each one of a plurality of hoppers, comprising:

• a plurality of sensor means each including a radiation source positioned on one side of an associated hopper and a radiation sensor positioned on an opposite side of said associated hopper, said radiation sensors being responsive to the incidence of radiation for generating pluralities of sensor output signals;
• central control means for periodically reading the output signals of each of said sensors for providing a summed signal corresponding to the rate of occurrence of said pluralities of output signals and for generating a status signal for each of said sensors when the amount of the material at an associated level in the associated hopper is a predetermined amount;
• and a plurality of indicator means each individual to one of the hoppers and responsive to an associated one of said status signals for indicating that the material in the associated hopper is at said predetermined amount.