I have a pulse encoder which I wish to connect to a PC via an interface = card. (the card includes other IC's and is still to be made) =20 The encoder has two digital outputs A+, A-, B+, B-. Two channels A and B = in quadrature ( 90 degree phase shifted). They are to connect to "Square = wave differential line driver to EIA RS422".=20 =20 After passing through the RS422 interface circuit the signals will be 5v = TTL signals ( A and B ) which are then to be connected to a suitable = up/down counter. The counter has to be at least 24bit (total count = 2500000). Counter frequency around 200kHz. Can be binary or BCD. The = counter contents have to be read on the fly. =20 Can someone help with=20 1. A suitable IC for the RS422 interface?=20 2. A suitable IC for the counter that can be interfaced to the BUS of a = PC. (either directly or via a buffer IC) I have checked the Farnell and RS catalogue both of which have many = RS422 IC's, but no up/own counters. =20 I am seeking assistance and advice from the list members. In both cases information on part numbers and web links would be = helpful. =20 Regards, Edgar. -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu