[HGen23] Heat generation, 1 boilers with external boiler control (on/off command, setpoint, feedback, common fault)

Boiler with external control, single-stage pump

Operating modes: Off, On

Components, sequence, and function in CMDSEQ_B

[CMDSEQ_B] Command sequence for binary

Start sequence

1. The pump and external control coil switch on at the same time (function AND, Group with next aggregate).

Stop sequence

1. External control switches off. It waits for 2 minutes (function Delay).
2. The pump switches off.

Plant operating modes:

• Off (1)
• On (2)

The operating modes are reported on [MCalcVal] object 'Present operating mode'.

At the same time, the reason for the present operating mode is reported to another [MCalcVal] object:

• Exception (1)
• Operating mode switch (2), resulting from an active (not equal to Auto) operating mode switch
• Operating mode (3), resulting from an active (not equal to Auto) manual operating mode selection
• Heat request (4)

There is a normal mode and exception mode.

Normal operation

Sources for normal mode:

• [MI] Operating mode switch
• [MCnfVal] Manual operating mode selection
• [HReq (1)] Heat request

In normal mode, in operating mode 'On', the boiler switches on with function block CMDSEQ_B.
[CMDSEQ_B] Command sequence for binary

Exception mode

Sources for exception mode:

• Fire detection contact
• Boiler faults: Heating pump fault, fault to external control of the boiler or triggering of the safety temperature limiter

In exception mode, all outputs are switched off directly at priority 5 and the present operating mode is set to 'Off'.

It is reported at input [RpdOff] for CMDSEQ_B on the boiler.

Start-up control (nested chart SttUpAlmHdl)

The following functionality is available for an automatic startup of the plant, e.g. after a loss of power and return of power:

1. Fixed switch-on delay (can be set on input pin [DlySttUp])
2. The plant remains off to ensure communications are reliable and cross-check references are triggered. 'Exception' is reported as the reason for the present operating mode.
2. Automatic acknowledge (2x) of possible pending alarms during a fixed switch-on delay.
3. Additional adjustable delay for staged plant ramp-up (can be set on input pin [DlyOn])

Alarm handling (nested chart SttUpAlmHdl)

The state of events on the plant is acquired by BACnet object 'Plant state'. The state is mapped on function block CMN_EVT.
[CMN_EVT] Common event

The following functions are available:

1. Automatic acknowledge (2x) after startup
2. Alarm acknowledgement with a value object
3. Alarm indication:
   - For pending alarms On
   - For unprocessed alarms flashing
4. Ability to connect the acknowledge button [BI]
5. Ability to connect to an alarm indication [BO], e.g. an alarm lamp through an output block [BO]
6. Ability to connect to other alarm handling functions on other plants, e.g. acknowledge button and alarm indication for multiple plants in the same control cabinet

Startup function and alarm handling for flat plants