Ken Parkyn wanted some information on the Wiegand format used by manufacturers of Access-Control systems... Here it is: Wiegand comes in a few different flavors... The most popular are the "26-bit" and "31-bit" formats. Data is organized as follows: 26-Bit Format: -------------- Bit 1 ------ Even Parity for bits 2-13. Bits 2-9 --- Site Code (also known as Facility Code). Bits 10-25 - PIN Code (also known as Card Number). Bit 26 ----- Odd Parity for bits 14-25. 31-Bit Format: -------------- Bit 1 ------ Even Parity for bits 2-16. Bits 2-14 -- Site Code (also known as Facility Code or Fixed Code). Bits 15-30 - PIN Code (also known as Card Number or ID Number). Bit 31 ----- Odd Parity for bits 16-30. The Site Code is the same on all cards at a given site. The PIN Code is different for each card. There are no errors or typos in the 'Parity" information in the above tables; the leading parity bit is even, the trailing one is odd, and in the 31-bit format, both use bit 16. Wiegand data is sent as a series of pulses over two data lines -- Each pulse on one line represents a zero and each pulse on the other represents a one. I still don't remember anything about the pulse timing, so you'll have to look at an existing Wiegand controller's outputs (or ask someone else) for this information. It's something real simple, like 1-millisecond pulses every 10 milliseconds. Hope this helps... -Andy Andrew Warren - fastfwd@ix.netcom.com Fast Forward Engineering, Vista, California http://www.geocities.com/SiliconValley/2499