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
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