The programmable controllers shall be 16bit type or more of the fully intelligent type, capable of performing all Control and Energy Management functions assigned to them, independent of any other BMS equipment.
Programmable controllers may be of modular or fixed hardware construction or a combination of both. The basic set of configuration data shall be held in permanent flash memory. The use of RAM is acceptable if it is battery backed.
In the event of loss of the main configuration data, the necessary data shall be downloaded from a back-up server automatically and without user instruction.
The controller shall have a self-analysis feature with in-built diagnostics and shall transmit any malfunction messages to the designated BMS terminal.
It shall be possible for the end user to add, delete, edit the input / output points from the BMS terminal without the requirement of any proprietary software or removal of LAN connections. An RS 232 port shall also be made available at the controller for connection of either a laptop, portable operators terminal or a modem.
The controller shall have its own real time clock and calendar to enable full stand- alone operation and shall have indication both of presence of power and of healthy operation. It shall be possible to reference the On/off-line State of programmable controllers, and each system communications port for display and alarm at the BMS.
The controller shall automatically align its totaled parameters such as hours run, meter points, self-learning parameters with the designated backup server at least once per day.
All software required to perform the operational functions of the system under normal operation shall be resident in the controller memory. In the event of the failure of communications between the controller and the BMS terminal, alarms, reports and logs shall be stored at the controller and transmitted to the BMS terminal on restoration of communications with a fully managed retry sequence based on priority and time. Programmable controllers shall store a minimum of 200 alarms.
Where information is required to be transmitted between controllers for the sharing of data such as outside air temperature, it shall be possible for global points to be allocated such that information may be transmitted either on change of status or at specific time interval. BMS Controllers shall be capable of monitoring and controlling the following hardware point types:
Inputs each with 12-bit resolution minimum shall be provided. Each input shall be capable of accepting typically signals of 0 – 10Vdc, 4-20mA, 0-10 ma, 0-1 ma or 0-10K ohms. The specialist BMS manufacturer shall provide suitable sensors and transducers to carry out the analogue monitoring shown on the point schedule.
Outputs each with 8-bit resolution minimum for modulating signal capability shall be provided (1 ma per channel ma at 10V output).
Voltage free SPST contacts (open/closed) <10K Ohms closed, >1M Ohms open.
Pulse input: Voltage free SPST contacts (open/closed) <10K Ohms closed, >1M Ohms open. These shall support a frequency of 10Hz. These inputs shall equally be able to be used for electrical maximum demand calculations.
Voltage free contact (rated at 230Vac 1A resistive) ON/OFF/AUTO override switches shall be integral and provided for each output including future expansion capability.
The specialist BMS manufacturer shall provide suitable actuators for valves, dampers to carry out the analogue control.
In addition to ports for networking to the controller network, controllers shall have at least one communications port for connecting peripheral devices such as a modem, portable operators terminal or BMS terminal.
Modular Programmable Controllers
- There shall be a model of programmable controller that is modular in construction and allow different combinations of input and outputs. It shall be provided where the hardware point count and mix warrants the use of this type of controller.
- Slots shall be provided for the insertion of plug-in function cards covering analogue inputs, digital inputs, analogue output, digital outputs and pulse counting inputs.
- Fixed input/output Programmable Controllers
- Programmable controller with a fixed input/output combination shall be provided where the hardware point count and mix warrants the use of this type of controller.
- Programmable controller with a fixed input/output combination shall have analogue inputs, digital inputs, analogue output, digital output and pulse counting input functions.
Where dedicated discrete controls are used for the control of fan coil units, chilled ceilings, lighting, Variable Air Volume Box controls or room control, it shall be possible to link them on a communications network like Bacnet, LonWorks® , LonMark®, Modbus, EIB etc. with full interoperability. This network may be a sub-LAN to the programmable controller or via router. The pre-programmed controllers shall be interrogated by the BMS terminal.
The system shall be able to utilise different protocols and architectures to maximise the media infrastructure.
The system offered shall ensure that different vendors shall be able to equally tender competitively, add and amend or change the system for future new sections.
It shall be possible for a list of parameters for individual controllers to be displayed at the BMS terminal. Any set-point parameters thus displayed shall be capable of being modified by the user and changes uploaded to the controller.
It shall be possible for the controls specialist to create or edit individual controller points at the BMS terminal so that new controllers may be added to the system or modified as required.
In the event of a failure of the communications network each controller shall be able to carry out full control functions in a stand-alone mode.
Each controller applied to fan coil or chilled ceiling applications shall have a minimum of 3 onboard relays rated at 230Vac, single phase, 5 amp resistive, 3 amp inductive and the controller shall be capable of being powered by 230Vac. These controllers shall have provision for connection of either conventional room thermostat or LCD display type thermostat and shall have the facility for the user to modify the set-point and the fan speed.
Each controller applied to variable air volume units with less than 6Nm torque shall have an integrated package of actuator, pressure transducer and controller for units below 6Nm and each controller applied to variable air volume units with more than 6Nm torque a separate VAV controller integrated with pressure transducer & a damper actuator of required torque. The VAV controllers shall have re-heat capability where heating would be required in the design. These controllers shall have provision for connection of either conventional room thermostat or LCD display type thermostat and dry contacts and shall have the facility for the user to modify the set-point.