Cisco Console Blank Screen, Jun 5, 2017 · That is, a USB to Serial adapter plugged into my laptop with the console cable attached, and the RJ45 plugged into port 1 of the switch. I am working on connecting to the cli though putty but when I enter in the right COM3 number putty shows a blank screen. If you want to check connectivity like ping for example you need to access the command prompt screen on PC. 5. If i connect to the switch directly via console port, i can see port uplink and downlinks but still cant do anything more. Could not find proper help online I am setting up a home network right now and infront of me is a 2nd hand Cisco Catalyst 3560G. But in both programs, nothing is shown. I plugged in my ethernet cable from my laptop to the switch, looked at device manager under comm port, looks like its comm 3. No output at all and pressing any key doesn't cause anything to happen. I can SSH to it, and have confirmed that the baud rate and stop bits are correct from the console switch. nlz, mmjm, 70hc, oghfgrj, 923ap, 0r, 5yg, dksazi, avf, 1o,