Working
The working of HACS model (shown in Figure 1) is explained:-
PC: PC being the main module has HACS system installed on it. The two subsystems; one being
appliances control is responsible for ubiquitous access of appliances and the second subsystem
being security alert is responsible for security intrusion detection. Both subsystems work on GSM
technology for transmission of instructions from sender to receiver.
GSM Modem: GSM modem is a plug and play device and is attached to the PC which then communicates
with the PC via RS232 port. GSM modem is a bridge responsible for enabling/
disabling of SMS capability.
Cell Phone: Mobile device communicates with the GSM Modem via radio waves. The mode of
communication is wireless and mechanism works on the GSM technology. Cell phone has a SIM
card and a GSM subscription. This cell phone number is configured on the system. User transmits
instructions via SMS and the system takes action against those instructions.