In one example, a fluid property sensor includes a proximal elongated circuit (EC), a distal EC, and an external interface. The proximal EC has multiple point sensors distributed along its length. The distal EC is extended in the direction of the length from a distal end of the proximal EC and is electrically coupled from the distal end of the proximal EC to a proximal end of the distal EC. The proximal and distal ECs share a common interface bus. The external interface is electrically coupled to a proximal end of the proximal EC. The proximal EC, the distal EC, and the external interface are packaged together to form the fluid property sensor.

A method for controlling a water heater appliance includes energizing the heating element for an energization period, such as less than two seconds. During the energization period, the appliance controller measures the electrical current passing through the heating element. The measured electrical current and a base signal are passed through a correlation filter to determine a correlation value. The base signal may correspond to the electrical current passing through the heating element when the tank is full or when the tank is empty, and the correlation value may be used to determine to which base signal the measured electrical current more closely correlates. In this manner, the correlation value is used to determine whether the heating element is submerged in water.

A method of detecting a level of printable fluid in a container includes, with at least one sensing location on a die in thermal contact with the printable fluid in the container, sensing a voltage of a capacitor over time as current from the capacitor leaks through a field effect transistor (FET). The FET and capacitor are associated with the sensing location. The method may further include, based on the voltage of the capacitor over time and a threshold voltage, determining whether the printable fluid is present at the at least one sensing location.

A logic circuitry package for a replaceable print apparatus component includes an interface to communicate with a print apparatus logic circuit, and at least one logic circuit to transmit, via the interface, a sensor ID parameter and a limit parameter, the sensor ID parameter indicating a first sensor ID. The logic circuit is to receive, via the interface, a first request corresponding to the first sensor ID with the component connected to the apparatus and the apparatus not pneumatically actuating the component. The logic circuit is to transmit, via the interface, a first digital value in response to the first request. The logic circuit is to receive, via the interface, a second request corresponding to the first sensor ID with the component connected to the apparatus and the apparatus pneumatically actuating the component. The logic circuit is to transmit, via the interface, a second digital value in response to the second request. A difference between the first digital value and the second digital value is greater than the limit parameter.

A logic circuitry package for a replaceable print apparatus component includes a first at least one analog cell of a first type, a second at least one analog cell of a second type, an analog-digital converter (ADC), an interface to communicate with a print apparatus logic circuit, and at least one logic circuit. The at least one logic circuit is configured to receive, via the interface, requests to perform measurements to selected ones of the at least one first and second analog cells. The at least one logic circuit is configured to selectively route analog signals from the selected analog cells to the ADC based on the requests.

A logic circuitry package for a replaceable print apparatus component includes an interface to communicate with a print apparatus logic circuit and at least one logic circuit to transmit, via the interface, a limit parameter and a count threshold parameter. The logic circuit is to receive, via the interface, initial requests to read sensor IDs with the component connected to the apparatus and the apparatus not pneumatically actuating the component. The logic circuit is to transmit, via the interface, a resting state digital value in response to each initial request. The logic circuit is to receive, via the interface, further requests to read the sensor IDs with the component connected to the apparatus and the apparatus pneumatically actuating the component. The logic circuit is to transmit, via the interface, a further digital value in response to each further request.

A logic circuitry package for a replaceable print apparatus component includes an interface to communicate with a print apparatus logic circuit, and at least one logic circuit to receive, via the interface, requests corresponding to different sensor IDs with the component connected to the apparatus. The logic circuit is to transmit, via the interface, a digital value in response to each request. The digital values corresponding to the different sensor IDs are distinct.

A logic circuitry package for a replaceable print apparatus component includes an interface to communicate with a print apparatus logic circuit and at least one logic circuit. The at least one logic circuit includes a memory storing at least one temperature calculation parameter. The at least one logic circuit is configured to receive, via the interface, a first request to read the at least one temperature calculation parameter; and transmit, via the interface, the at least one temperature calculation parameter in response to the first request. The at least one logic circuit is configured to receive, via the interface, a second request corresponding to a sensor ID; and transmit, via the interface, a digital value in response to the second request. The digital value adjusted based on the at least one temperature calculation parameter corresponds to an absolute temperature of the print apparatus component.

A kit for connecting to, and monitoring fill levels of a fluid storage tank includes a control module and primary and secondary sensor units. The control module is electronically connected to the primary sensor unit. The control module includes a circuit board with a microprocessor, memory unit, and transmitter. Each sensor unit includes a housing a seal attached to the housing around an opening thereof, attachment structure for attaching the housing to a wall of the tank, and an infrared sensor disposed in the housing proximate the opening. The primary sensor unit also includes a circuit board disposed within the housing, an ambient temperature sensor disposed in the housing, and a communications link for communicating with the control module. A method of monitoring a fluid level in a storage tank, and a system for monitoring and reporting fluid levels in a plurality of storage tanks, are also described.

An example printing cartridge includes a fluid container, a sensing die including a plurality of sensing locations in thermal contact with the fluid container, and a voltage comparator to output time-based information by comparing a sensed voltage generated at a selected sensing location of the plurality of sensing locations to a threshold voltage, the time-based information representative of whether a fluid is present at the sensing location.