Chapter 11 - Typical Monitoring and Control Systems

Conventional monitoring and control systems

Poultry house control systems in the U.S. typically consist of single or multiple stage thermostats which control ventilation rate by regulating the position of curtains or damper inlets along the side of the house and/or the number of fans being operated. For hot weather, a separate thermostat or one of the upper stages of a multiple-stage thermostat may be used to control evaporative coolers – usually by turning water supply valves or pumps on or off. Lights are typically controlled by electromechanical timers. Other variables like humidity, static pressure and ammonia are not usually controlled.

Monitoring is usually restricted to house temperature using glass or dial thermometers hanging in the house in the exhaust air stream. Light levels may be spot checked with hand-held meters. Humidity and ammonia are usually not measured, but producers usually try to make adjustments in ventilation rates or set points based on perceived humidity levels or ammonia levels in the poultry house. Alarms are usually limited to audible devices which can be heard at nearby farm offices or homes, and which can be triggered by power failures (which would result in a loss of ventilation in the event of powered ventilation systems), high temperatures, or failure of the watering system. Some alarm systems use regular wired or cellular telephones with automated dial out triggered by out-of-range variables to deliver trouble messages stored on tape or in solid-state memory.

Electronic and computer-based monitoring and control systems

A variety of commercial monitoring and control systems are available which utilize electronic controls and remote sensors. The remote sensors may be located anywhere from a few feet from the controller to several hundred feet depending on the application. Excellent, highly reliable sensors are available for temperature, humidity, light level, and static pressure measurements – the most commonly monitored variables in poultry houses.

Dedicated electronic monitoring and control systems

Depending on the configuration, these systems are used on individual houses to provide anything from an electronic version of the electromechanical thermostatic with a readout at the unit, to multiple sensor systems that can control temperature, humidity, static pressure, evaporative coolers, supplemental heaters and/or brooding systems, lights, and ventilation rate with readouts at the unit.

Distributed electronic monitoring and control systems

Depending on the configuration, these systems can provide the same functions as the dedicated electronic controls described above, and they can also be linked together to a central computer which can be used to monitor and record events and conditions at various locations. Conditions can usually be monitored on the dedicated controller at each house or at the central monitoring point which can usually be located anywhere from several hundred feet to miles from the houses being controlled, or monitoring and control can be done by telephone using dedicated lines. Environmental conditions can usually be logged at the central location. Alarms for out-of-range variables can usually be indicated (visually or audibly) at both the individual and central locations. Failure of one ore more of the dedicated control systems or the communication link between the central location and the remote buildings does not affect any of the other systems in a multiple house system.

Central computer-based monitoring and control systems

These systems can control single or multiple houses, and they usually use remote input/output boards at each location to interface to sensors and control outputs. Monitoring, logging and alarming are all programmed and controlled from the central computer. Failure of the central computer or a communication link between the computer and the remote input output boards will cause loss of control unless appropriate backup systems are provided. Automatic backup systems for computer-based control systems are readily available, and they have been proven to be very reliable in recent years.

An example of a commercially available, computer-based central monitoring and control system is given below. In this system, a PC communicates with equipment located throughout a typical poultry farm. A farm manager has the ability to monitor conditions and operations in each broiler. Schedules for temperature, lights, and feeders in each house are set at the central computer. At any time, a farm manager can monitor conditions remotely, change current set points and schedules, and get reports. With a modem in the control computer and a remote computer and access to a telephone line, these capabilities are available to a farm manager anywhere.