remote monitoring

What are the choices for remotely monitoring analog signals?
The site has a copper phone line that is shared by a phone and fax. Once a month or so two analog voltages must be sent to a remote computer for record keeping.
Wireless, cellular, laser, and so forth are not options or required. If one connection is made within 90 days all is good. This is a low hazard system. Very low. Currently pen and paper does the job. (When the operator remembers.)

The voltages are 1-100VDC and .01 to 5VDC. Typically they change about +/- 10%/year.

The lower the cost the better due to the ease of using a pen and paper.

TIA

Tom

THIS looks like it might do the trick. Most of the autodialers I've seen can only report discrete 'alarm' conditions (i.e. over/under consitions), but it supposedly this one can fax specific values from it's log files.

Probably not cheap though...



-Eric

What about a system to SMS the data? A simple RTU or even something made from an electronics hobby store could suffice.

EDIT: SMS in aus is a mobile phone text message!

Honga,

Thank you for your comments.

With the potential of thousands of systems being monitored. it must be a simple two-number data transfer once a month. From there, a computer program will have to evaluate the most recent data and compare it to past data and only alarm if it is >10%< (for example). Otherwise it becomes too difficult to deal with.

The simple RTU (http://autoelect.com/products/controllers/srtu/index.shtml) appears to be a device for communications over a network. Is that correct?

What do you have in mind from an electronics hobby store?

Eric Nelson,

Thanks for your comment.

It looks like a bit too much (pun intended). However, they may have some old devices that may work. There is a lot of equipment on their web site. (Still looking...)