stewe@opal.cs.tu-berlin.de (Stephan Wenger) (05/29/91)
Hello, this is my first posting to the net, so please be patient about the "netiquette" and my English. I have a hardware (?) problem concerning the c004 Linkswitch. I have build a wrapped prototype board with one T800 and one c004. The links 0..31 of the c004 are connected via a backplane to 8 T800 which will do the work I need. All links are bufferd by 74AC244 and have matching 75 Ohm resistors on the transmitter and 1 kO pulldowns at the receiver. The longests connection on the (wrapped) backplane is about 20 cm. The link 31 of the c004 is connected to the link 2 of the T800 on this board to allow network-loading. I use the tds2 (D700c) Network-Tester after programming and verifying the c004. Even if only two links are connected, i get "Link Error 17" and sometimes various token errors. I have tried to wrap a quick hack, which plugs into the backplane instead of the prototype-board, and everything works fine. All the signals look fine (nearly no undershoot etc.) and VCC, GND and decoupling is also ok. My questions: 1. Has anybody out there solved a similar problem? Hints are welcome. 2. My application-SW (very low Link-Traffic) seems to work fine. Maybe I have a software-problem. Is it possible, that the searching-worm of the network-tester disconnect links, resets the link-switch, or something else? Replies per email please. I will post a summary if requested. Yours Stephan Wenger stewe@opal stewe@tub