V-Link RTU This Project was submitted to Parallax by Bill Isherwood VLink started after a dead-end  search for a small useful RTU device that could be solar or conventional powered, was relatively small and priced around $500. The typically available RTUs are fairly large, require high current drain and cost $2000 and up. Not being able to find exactly what I wanted for the rural water supply market, I decided to produce my own product: 'VersaLINK RTU'. The heart of VLink is the Parallax, Inc. BASIC Stamp® 2 module. VLink is versatile in that it can be powered from 8 to 24 VDC and easily configured to consume very little energy for solar powered application. It can communicate using RS232, up to 19200 bps, utilizing several standard radio modems or VLink can be configured to communicate over conventional FM voice radio or telephone path using DTMF tones. VLink is a small 3" x 4.5" PC board that fits standard snap track for mounting.  VLink currently utilizes only about half of the flash and RAM resource leaving enough memory for custom applications. VLink series includes ISO optically isolated solid-state I/O relays for interfacing to just about any voltage device.