Post by thread:Re[2]: RS-422

>I'm searching to for such a protocol too. Ofcourse it's not very difficult I've seen dozens and dozens of "non-standard" protocols that are variations on a single, simple theme. Send a SYNC byte, an Address, data and a CRC. Use a Master-Slave scheme with timeouts and ACKs. Do this, and you are done. Move on. Works great. Maybe this is a "conceptual standard". I guess the CRC-16 is a standard... I'm not sure what another standard buys you. I've written a variety of PC-based master devices to do the serial, written in VB or C and the serial protocol part of it is, maybe, 50 lines of code (including comments). I am not against reuse nor standards, however, I've seen tooooo many systems that are large, cumbersome and expensive because of slavish adherence to a standard that was 10 times more complex than required for the simple application at hand. Just my 2-cents. I'm concerned about Fat-Ware and Overdesigned systems I've been having to deal with lately. My apologies to the original poster.. spam_OUTThomas.CoonanTakeThisOuTSciatl.com

Just a small addition to all this packet formatting talk... And, don't forget the Base-64 tricks. *If* you like ASCII (better for debugging) and you want to send binary values (like a long int) over the wire, then use can use Base-64 encoding. You *could* simply use HEX encoding with a heavy bandwidth penalty. Base-64 is a compromise. You can define 1-byte, 2-byte and 3-byte base-64 arguments for any particular field. Base-64 says that all ASCII message characters (except start and stop framing characters) are constrained to the ASCII range of '0' thru 'o' (which is 64 characters, which is 6 bits). Then, to encode a 16 bit binary number, you break it into 3 Base-64 character (6 bits each). binary Base-64 string (I use ASCII '0' as base character) Eg. 40233 --> 9dY 0 --> 000 1 --> 001 63 --> 00o The conversion routines are pretty simple. If you're happy with binary with ESCAPE coding for the framing characters, then ignore all the above! .....Thomas.CoonanKILLspam@spam@Sciatl.com