Home Toys Article
- October 2004 -
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No cost / Low cost Web based monitoring system using your computer, and a free web based service from BroadBandSentry.com
By Gary Drake - www.BroadBandSentry.com

As we have shown in the past simple interfaces can be created to use the existing computer and the Internet. No need to wonder about the state of your home , vacation home or office


1) Introduction
BroadBandSentry is please to introduce with this article our No cost / Low cost Web based monitoring system using your computer, and a free web based service from www.BroadBandSentry.com. Now everyone with a Internet enabled computer has the makings of a home, vacation home or office monitoring system. Combining the existing hardware on a personal computer with simple external sensors, everyone can have peace of mind about their home, vacation homes, or office. In the last two issues of Hometoys we have presented a simple water sensor and temperature switch, these concepts apply here as well.

You will be using your computer as a client, meaning that it communicates with a remote server (BroadBandSentry.com). Perhaps the easiest way to think of it is when you use a Browser to access a web page, such as www.BroadBandSentry.com for example. The Browser on your computer is functioning as a client, and you are communicating with the web page server. We use the same concept for the client service. By combining a web service (www.BroadBandSentry.com) with the client program the status of a serial port is reported. The www.BroadBandSentry.com servers interpret these messages and will send email alerts based on information you have entered at www.BroadBandSentry.com.

The software running on your computer is a client to www.BroadBandSentry.com, exactly like a Browser or Email program. No modifications to any networking software, firewalls, etc. are required. Your computer sends a short string containing sequence five true or false words. The interpretation of the string is done at www.BroadBandSentry.com, messages based on the sequence are created by you.

For NO cost peace of mind using the www.BroadBandSentry.com service a version of the client uses no serial ports. The only information reported is that your computer contacted the www.BroadBandSentry.com service. With this simple implementation you can configure an alert to inform you that your computer fail to update www.BroadBandSentry.com , lost power?? ISP down??? Simply knowing 24/7 about the state of your electricity can be reassuring.

2) Serial Port

Serial Ports are used to communicate as the name implies in a serial fashion to some other serial device. Before USB or PS2, mice often used the serial port. A serial port can contain 9 or 25 pins,.

On the back of your computer you have a connector like the picture to the left:

The mating connector is available at local electronics parts stores (Radio Shack for example):

The pins on the back are called solder tails, and are designed for soldiering discreet wires into.

These connectors work well with the ideas for simple sensors in my previous two articles here at www.HomeToys.com.

RS-232 SERIAL (COM) PC PORT CONNECTOR DB-9

DB-9 PIN (Male) FUNCTION ABBREVIATION
1 Data Carrier Detect CD
2 Receive Data RD or RX
3 Transmitted Data TX or TD
4 Data Terminal Ready DTR
5 Signal Ground GND
6 Data Set Ready DSR
7 Request To Send RTS
8 Clear To Send CTS
9 Ring Indicator RI

The pin numbering of the connector is often embossed in the plastic portion on the connector.

Some computer do have a larger 25 pin connector. The same connections we used for the 9 pin connector are used in the 25 pin connector. Note the pin numbers have changed, these connectors as well are available from your local electronics parts store.

RS-232 SERIAL (COM) PC PORT CONNECTOR DB-25

DB-25 PIN (Male) FUNCTION       ABBREVIATION
1 Chassis/Frame Ground GND
2 Transmitted Data TX or TD
3 Receive Data RX or RD
4 Request To Send RTS
5 Clear To Send CTS
6 Data Set Ready   DSR
7 Signal Ground  GND
8 Data Carrier Detect DCD or CD
9 Transmit + (Current loop) TD+
11 Transmit - (Current Loop) TD-
18 Receive + (Current Loop) RD+
20 Data Terminal Ready DTR
22 Ring Indicator  RI
25 Receive - (Current Loop)  RD-

We are using five of the pins, CD, CTS, DSR, DTR, RTS. Of these five pins three are inputs only (CD, CTS, DSR) and two are inputs and outputs ( DTR, RTS ). There are several different versions of the UPLINK program, ranging from 3 inputs using 2 of the pins (DTR, RTS) to supply a switch able voltage, to versions using all five inputs (requiring external power).

The simplest approach is to use a switch or relay closure between CD & DTR, CTS & RTS. DTR and RTS supply the required voltage for CD and DTR to sense. A wall thermostat as suggest in my previous articles here in www.HomeToys.com , as well as the other simple devices in those articles can be used. These include the water switch, relays, and magnetic switches. It again should be noted that these are RS-232 interfaces, and can only be used with Direct Current (DC) voltages. RS232 operates at +12V to -12V where:

Signal = 0 ( false ) > +3.0V
Signal = 1 ( true ) < -3.0V

A web search will surface numerous references on RS-232. Here we will be using only the status bits, not the serial data ability of a serial port.

3) Using the BroadBandSentry Web service

BroadBandSentry is a server based application, with only a small client program (see below) running on your local computer. You can register for the FREE service or choose one of the Subscription plans. After the registration screen you are presented with the screen to create an entry similar to the one below.

 Enabled 150520 / 600s office / ...     ...
  Uplink Serial Port@ ... : 80   MAC Address: 00-0C-41-1C-16-EB   COM Port: COM1   User: ...  Password: ...
    Frequency: Select Frequency     Add the update Frequency
    Times of operations:   00:00:00 - 00:00:00      Enter the times of operation
     uplink, ..      Add a State to this Function
         String Found      Add a Action to this State
            Find this sting: true:false:false:true:true
             Send Message
     Customize this Action
                 myemail@myemail.com, Water!!!!!!!!!!!      Edit this Message

This description is entered via your web browser, it specifies that www.BroadBandSentry.com should accept client data from the computer at "MAC Address: 00-0C-41-1C-16-EB COM Port: COM1" The client sends a string that contains "true:false:false:true:true ". The string defines the water switch having been activated. An email message will be sent to the specified email address. We can specify more then one-email address, your phone, your office, your neighbors, and other family members.

Actions to a state include String Not Found, and No Response (used to inform you that we have not heard from your computer in the allotted time interval).

4) Installation of client software

The client software is available for download from www.BroadBandSentry.com, links are provided for each version, No Port: COM1: COM2: COM3: COM4: COM5: COM6: You need only the version for the port(s) you plan to use. Individual versions for each port have been created to simplify the user interface, there are no configuration switches or files to set. The program automatically connects to www.BroadBandSentry.com, updating the state of the serial status pins. The serial ports number and other information about your computer is accessible via the control panel. There are no changes, and no settings to change on your computer to use the UPLINK client.

Should you not have a serial port available on your computer, but do have USB, a Serial to USB converter will work. Follow the instruction from the supplier of your convert to install the required drivers, identify what COM port number it was assigned (windows control panel).

There are versions available for Dos and a Windows. The windows version displays the last time the update was sent and the status string sent.

5) Summary

www.BroadBandSentry.com and the client allows every owner of a Internet enabled computer to have a personal monitoring system, at little or no cost. We have presented here the use of our FREE monitoring service, enhanced services are available for a subscription fee. The FREE service allows for hourly updates from your computer to our server with Email notifications sent to you. The subscription services offer enhanced update functionality and enhanced notification option.

Some of the enhanced features are:

  • Automated Voice notification
  • Image Capture via Client
  • Immediate Client updates on Changes of Sensors
  • Client that reads serial data in, Sends serial data to www.BroadBandSentry.com, and manages Serial control pins.
  • Client that controls Parallel port output pins, control pins.
  • Client polling of other Ethernet devices on your local net. See my previous articles on www.HomeToys.com for examples.
  • With more to come!!!

As we have shown in the past simple interfaces can be created to use the existing computer and the Internet. No need to wonder about the state of your home , vacation home or office From the simple its alive and communicating. To temperature or water switches. To imaging, and sound alerts (enhanced service for a subscription fee). By combining your computer, the Internet, software and services from www.BroadBandSentry.com your world can stay in touch with you!

Several remote sensors, cables, connectors, etc. are available from www.BroadBandSentry.com for use with the FREE, and enhanced services.

BroadBandSentry is a trademark of C.S.D. inc. www.BroadbandSentry.com

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