One of the most straight-forward uses for the Redirector is the replacement of a simple serial cable.
Some of the drawbacks of RS232 cables are:
- Serial cables are limited in length. Just how long a serial cable can be depends on many factors, but a commonly used number is 50 feet. Serial cables can be much long, many hundreds or even thousands of feet, but guaranteeing reliable communication at greater distances is more luck than science. The traditional answer is to use line drivers to convert RS232 to a proprietary format and then carry that over twisted pair cabling.
- Serial cables need to have several cores, depending on which control signals require to be carried
- There are no recognized standards for carrying RS232 data across structured wiring. (If you need to do this, then the DEC standards as used by the DECServer 700 series terminal servers appears to be better than most schemes.)
The approach using the Redirector is to use a terminal server at one end of the link, and the Redirector software on the PC.
It is now possible to buy terminal servers at low cost. Using a terminal server and the Redirector may actually work out cheaper than even a newly installed 50 foot run of RS232 cable.
The lowest cost terminal server we are aware of which we have actually used is the SitePlayer telnet box which at the time of writing is $79 US. See the SitePlayer web site.
For a real world example of replacing a serial cable, see Interfacing to X10 over IP.