eye_sky1 0 Posted May 1, 2009 I am running a Pelco 9760 matrix and I have a 9760 keyboard that is wired with the straight cable from the cc1 to the power pac and a reversed cable from the power pac to the keyboard and it works. Can anyone explain how this is working? Only the one 9760 keyboard will work with it all the others state keyboard offline. I am not sure how it got installed this way but it would have been working for about 5 years since the workstation was moved. I only found it because the keyboard has started jumping to the left and I went to change it out with a different one. Share this post Link to post Share on other sites
survtech 0 Posted May 1, 2009 Interesting! The keyboard probably has a full wave rectifier bridge inside to protect against reversed polarity of the power. For the data, it wouldn't matter as long as one cable was straight and one cable was reversed, since the data just has to go through one "twist" somewhere. The pin functions for the RS-422 port on the keyboard are: 1. RS-422 TX + 2. RS-422 TX - 3. - 4. + 12VDC In 5. Ground (Power) 6. - 7. RS-422 RX - 8. RS-422 RX + Pins 1/2 and 7/8 have to be reversed somewhere in the loop. The power supply data connection is straight through. If pins 4 and 5 are reversed, as would happen if the cables were swapped, normally the keyboard would fry without an internal protection circuit. By the way, we have a full CM-9760 800x32 system for sale. We will split it up into chunks if you need anything. PM me for details. Share this post Link to post Share on other sites
