When there are relay and input boards to control on a remote serial line the normal method is to use the COM1 or COM2 serial port. These ports are limited in comms speed to a maximum of 115Kbaud. If you are working under Windows then the limit may be as low as 19.2kbaud.

To communicate with a remote board a message is built up and sent out the serial port. The response is received and has to be analysed. If there has been a communication error (determined by a checksum or CRC) then a second and perhaps third attempt must be made. If there is no response from a board address then the routines must timeout and report an error.

All this can be avoided by letting the Control-it 5101 do the job. It has an on board computer to handle all the communications and re-tries, and can do all this at 690kbytes/second. Because of its compact binary protocol, performance is 10 times greater than the equivalent system running an ASCII based protocol at 115kbaud. The board does not need a free comms channel, does not tie up any interrupt lines, and does not require DMA (Direct Memory Access).

The Control-it 5101 is a win-win situation. Your PC does not have to labour away getting data from remote boards, and the Control-it 5101 does it 10 times faster.

And it's so easy to switch or read remote inputs and outputs. The supplied dll provides plain language commands that support all software languages, with examples in C++, Visual Basic & Delphi. As an example, a digital output is controlled by specifiying the module number, output number and whether you want it On or Off. As easy as that.