Hardware Points

Hardware points are points that can be physically wired or connected through a wireless sensor to the terminal strip of a controller. They include field devices such as relays, actuators and sensors. Their function is to transmit data back to the controller or physically carry through a CBAS command.

There are four main types of hardware points. They are analog inputs, analog outputs, binary inputs, and binary outputs. Binary points have only two states such as ON/OFF, OPEN/CLOSE, or START/STOP. Analog points on the other hand, represent a range of measurement such as a temperature of 0°F to 110°F, a pressure of 1psi to 5psi, or a flow rate of 100 CFM to 200 CFM.

Whether a point is Binary or Analog, it must be either an input or an output. Points that monitor the status of a field device are inputs. Field devices send their condition or quantity to an input on the controller.

Points that control the status of a field device are outputs. The user can either control outputs manually, or allow for automatic control based on schedule, logic, PID, or other software outputs programmed in CBAS.

In addition to the four main point types, points can be IN/OUT, supervised, or counter.

• IN/OUT points – A separate input can be used to verify that a field device responded to an output. When these two points are linked, it becomes one point called an IN/OUT point. For example, a relay that turns an AHU on when contact is made is a binary output. A pressure sensor in the duct that indicates an increase or decrease in differential pressure in order to verify that the unit turned on when commanded is an analog input. When the relay output and differential pressure input are linked, the operator can command the AHU to start and watch the status change from OFF to ON through a single point.

• Supervised Points – Monitors the consistency of a wire. Sends one of a possible three states: Open, Closed, or Trouble. Trouble is how CBAS defines a broken connection between the controller and the point. For example, if a door is normally closed, a binary point would indicate an open or closed door. A supervised point would do the same thing, but would also indicate when the wire connected from the controller to the door monitor has been tampered with.

• Counter Points – Counts the number of times that a binary point changed status. These are most often used in Kilowatt (KW) meters for monitoring power usage. This number is constantly increasing and rolls over to 0 when it reaches 65535. As of CBAS Version 2.2.6, the Counter point stores up to 4,000,000.00