Sending messages from area A to area B via telephone line.

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Thread Starter

Eng. Zahi KHAWAND

Dear Sir; Hi men; Could you please give me a solution concerning the transmission of a fault (e.g: dry contact#4) via a telephone line from Area A in order to display a message (e.g.: Problem in Pump# 4 !) on a personal computer located in Area B. N.B: 1-Can I find a KIT which contains a Transceiver + Receiver + Software in order to solve the above mentioned problem? 2-Please note that four other stations similar to the station#1 in area A have also to report a fault to the same personal computer in area B!
 
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Christian Felde

This might be a long shot, but here goes; You take a PLC. This PLC needs to have an serial-port of the type RS-232 (if it has some other RS-type, you could use some converter to get it to RS-232). You also need to be able to have full control over this serial-port via program commands within the PLC. Then you take a normal analog modem and connect to this serial-port and to a telephone line. Then connect the error signals to different inputs at the PLC. On the PC, you also naturally connect a modem. Configure this modem to automatically answer any incoming call. Open a normal modem-terminal witch is communicating with the modem. Now make a program for the PLC witch does the following; On an error, make the PLC call up a number via the modem. The other modem needs to be connected to this number. On connect, send out an error description to the modem. This is sent as clear text. Then hang-up. Now, at the terminal on the PC, you have the error message displayed. This isn't any elegant solution, but it is one that will work. It really isn't any huge problem making a PLC use a modem if you have as much control as needed over the serial-port. I have done this ones using a Siemens PLC. - Christian Felde
 
One of our customers connects our dry contact products to phone lines using the same principal as you would with a window security system. (magnet / reed, on off switch on a window) Several cost effective products are available for your application. Look in your local consumer electronic stores for systems - ready to run. The something? 10 product works well. We have an open board product - connects to PC port, if you can't find anything local. Thanks Bob Hogg www.almegcontrols.com
 
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Eng. Zahi KHAWAND

Hi Christian F.; I wanna thank U for your valuable response concerning the Data Acquisition Sys.of my project. But in order to do it ,could U please send me a copy of your siemens PLC program which is already done. By the way ,how did U read (or display) the information on your PC? Thank you. N.B: You can contact me directly at: [email protected]
 
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Christian Felde

Sorry, I don't have access to the PLC-program anymore. It's about a year ago I made it. Nor do I have access to the PLC documentation here now, so I don't remember what commands where in use to issue the send and receive. But it really isn't any big problem if you understand the language. Just study it a little while. On the PC, just use any normal terminal program witch can communicate with a modem using a serial line.
 
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I know of a company that offers a remote control box that sends faults messages and I/O information to remote locations thru a GSM satellite cellular device. It works like having the machine make a cellular phone call with the fault information provided. The nice feature is that you can also program back a fault recovery action the other way to begin some type of corrective procedure at the machine. It's fairly inexpensive and it appears to be a great solution unless there's some reason you must use the phone land line. The company it's available through is called Engineering Technologies Inc. (engineeringtech.com) My suggestion is to e-mail them from their website. I see their device as a great solution for remote pump houses for example, where the performance of that control system must constantly be maintained. If I have a pump go down 100 miles away, I will know it within seconds and depending on the design of the control system involved, I can for instance start a back-up pump via cellular transmission until I can get someone to the site for troubleshooting. The overall impact is greatly minimized. Obviously there are RF solutions as well, but they are far most expensive and the performance difference is night and day.
 
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Paul Reynolds

Barton Instruments makes a RTU calles the DataSCan DS 41/41. It will take in 6 analog inputs and 2 contact closures, 7 additional digital inputs are available as an option. You can configure 3 alarms per inputs. Barton has a simple window based PC program that can be used at your B location to receive the alarms. You can find out more by visiting our website at www.barton-instruments.com.
 
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