26-bit is the length of the Wiegand number.
If the site already uses another bit length, stay on that format or re-issue cards and reprogram the panel together.
26-bit Wiegand
A 26-bit Wiegand card format. Cards, reader, and panel must share this length.
Also called
26-bit26 bit WiegandH1030126-bit Wiegandwiegand bits 26 bit
Catalog fields
Wiegand Bits
Source: Transmitter Solutions product training