External Entity-Relationship Diagram

Kendall & Kendall (2014), Entity relationship diagram in software engineering denotes to the process of pictorial representation of attributes, relationships and entities. It provides the relationships for database in software design system. In the figure below we present a visual concept of Central Heating System Version 10 (CHCV10). It pictures out how the inside of the system interacts with the outside environment. In the visual diagram, modalities and cardinalities together with their relationships are presented 

The central heating system has only one control panel board. This control panel coordinates system activities.

• Each subsystem control panel has more than one or zero operators.
• In the ER diagram the supplied gas to the room is blown with one or more pipes
• Gas supply comes from one and only one supply pipe.

Laplante & Ovaska, (2012).

Context Diagram

Pressman, (2010), context diagram defines certain boundaries in a particular environment or system. 

CHCV10 provides boundaries in the system.

• This CHCV10 is the explained system in the assignment as Heating Water Company
• There exists physical entities in the system such as gas supply pipes, clock system,

Data and Control Flow Diagram 

Assumptions made

• Manual control system receive information from operator
• Operations such as stop, start controls the heating system
• Gas filling source information from temperature system

CFD Gas Duct Control System 

 Kopetz, (2011), describes process specification as a method deployed to document, analyse and explain decision making logic and formulas used to produce information from the input process information. Gomaa, (1993), the process basically flows down specifying engineering requirements and methods. Below are design language for our CHCVS10 system.

Heating Duct

if pipe duct closed manually

            then

                        open it manually again

                        else if

                                    heating duct system closed by CHCSV10

                        then

                                     open heating duct system  by CHCSV10

                        end if

            if central heating system working

            then

                        pipe duct system report status

                        else if

                                    no status report

                        end if

            if new active status determined

            then

                        display new status alerts

            else

                        display latter status

end

System Clock

if power energy is available

            then

                        clock system  always on

            else if

            power energy  backup available

            then

                        clocking system is always on

end

Temperature Detector System

if power available

            then

                        temperature detector system is on

                        else if

                                    power backup energy available

                        then

                                    temperature detector System on

                        end if

            if central system working

                        then

                                    temperature detector system send temperature status alerts to monitor display

            else

                        no temperature alerts display

            end

Heating Unit

if

            <50% of pipe ducts are open

            then

                        heating system turned on

            else if

                        room temperature falls below minimum required

                        then room heated

            until    

                        room temperature measured is above range

            else

                        no heating alert displayed

            then

                        heating system is turned on manually

end

Gas Meter Supply

if

            gas supplied is available

then    

            record of available gas is obtained.

            else if

                        gas supplied in not available

            then

                        no record of gas supplied

                        end if

            else if

                        gas supply is  unavailable

            then

                        gas supply is stopped

            end if

end

System control

if

            time of the day is between 12:00:00 am and 5:59:00 am

            then

                        room temperature range of 5 to 10 degrees Celsius maintained

            else

                        turn on heating system

                        else if

                                    time of the day is between 7:00:00 am 5:59:00 pm

                        then

            room temperature of 15 to 20 kept constant

                        else if

time of the day is between 6:00:00 pm and 11:59:00 pm

                        then

                                    room temperature of 5 and 10 kept constant

                        else if

                                    manual heating is set to certain temperature

                                    then override automatic heating system

                        until

                                    heating system  is scheduled to turn on

                        else if

                                    Fan and Heating unit are turned on

            then

                        turn on automatic heating system

                        else

            heating system shows updated room temperature status

end

Control Specifications (CSPECs)

Krishna, (2011), describes Control Specifications as the parameters of a physical production techniques. Krishna, (2011), CSPECs mimics system behavior from different level of operation to another level. Our CHCSV10 has the following Control Specifications:

State machine

Process activation table

Input Actions
Start or Stop	0	1	0	0	0	0
Screen Monitor event status finished	0	0	0	1	0	0
Gas notification	0	0	1	1	0	0
Timing out	0	0	0	0	0	1
Display action status Incomplete	0	0	1	0	0	0
Sensor activity	0	0	0	0	1	0
Output
Signal of Temperature	0	0	0	0	1	0
Process activation
User Interruption	1	0	0	1	0	1
Invoke/Deactivate heating system	0	1	0	0	0	0
Show statuses and messages	1	0	1	1	1	1
System Control and Screen Monitor	0	1	0	0	1	1

 

Water Heating Company CHCSV10 Data Dictionary.

DeMarco & DeMarco, (1999), a data dictionary refers to a description of informational entities in a data modelling. It benefits programmers who use the data dictionaries as a point of reference during their coding activities. The following is CHCSV10 data dictionary.

Data Structure
Gas from fanning system	Volume: as required Temperature: as required in degrees Celsius
Flow rate: as adjusted
Normal gas	Normal gas = Natural gas
Warm gas	heated gas=
——- Flow rate: as adjusted in m/s
Temperature: as required in degrees Celsius
Volume: as required

 

Gas supplied in the room	Volume: as required Temperature: as needed in degrees Celsius
Flow rate: as adjusted

 

Supplied gas	Supplied gas =
———
Volume : as required Flow rate: as required
Other versions: filtered or unfiltered

References

DeMarco, P., & DeMarco, G. (1999). Building Architectural Models. Atglen: Schiffer Pub.

Gomaa, H. (1993). Software design methods for concurrent and real-time systems. Addison-Wesley Longman Publishing Co., Inc…

Hatley, D., & Pirbhai, ‎. (2013). Strategies for Real-Time System Specification. Boston: Addison-Wesley.

Kendall, K.E. & Kendall, J.E. (2014). Systems Analysis and Design (9th Ed.). Harlow, England: Pearson Education Inc.

Kopetz, H. (2011). Real-time systems: design principles for distributed embedded applications. Springer Science & Business Media.

Krishna, C. M. (2011). Real?Time Systems. Wiley Encyclopedia of Electrical and Electronics Engineering. Northcutt, J. D. (2014). Mechanisms for reliable distributed real-time operating systems: The Alpha Kernel (Vol. 16). Academic Press.

Laplante, P. A. & Ovaska, S. J. (2012). Real-Time Systems Design and Analysis: Tools for the Practitioner

Pressman, R.S. (2010). Software Engineering: A Practitioners Approach (7th Ed.). McGraw-Hill. ISBN: 978-007-126782-3