node = 7.61 (BITXOO) NCP> %%%%%%%%%%% OPCOM 1-MAY-2013 18:46:32.05 %%%%%%%%%%% Message from user DECNET on BITXR1 DECnet event 4.7, circuit down, circuit fault From node 7.92 (BITXR1), 1-MAY- 2013 18:46:32.05 Circuit TX-1-7, Line synchronization lost My setup is as follows: 7.92 (experimental machine): sim> show vh VH address=20000140-2000017F*, vector=2C8-2E4*, lines=32, 4 units VH0 attached to 32011,Line=15,Connect=192.168.0.8:32024;notelnet,32024;notelnet, DHV mode, 1 connection VH1 DHV mode VH2 DHV mode VH3 DHV mode BITXOO: sim> show vh VH address=2013E140-2013E14F*, vector=E8-EC*, lines=16 attached to 32023,Line=15,Connect=192.168.0.2:32024;notelnet,32024;notelnet, DHU mode, Modem Hangup, 2 connections sim> BITXOO is running VMS 4.7, and it is a simulated 780. The other machine is running 7.3 and it is a virtual 3900... Anyone has been succesful setting this thing up? Hmmm... I've tested this with DZ devices on windows hosts and not seen circuits popping up and down... I would work with the DZ device first. It has been tested and had its modem related behaviors more solidly verified. By the way, you shouldn't need to disable telnet as long as you have the telnet setting the same on both ends of the connection (i.e. notelnet<->notelnet or telnet<->telnet). The telnet setup we are using provides an 8 bit clean binary telnet channel. I would make sure that you've have MODEM and HANGUP settings enabled on both ends (from the simh perspective). What do you have for /MODEM and /HANGUP settings on the VMS ports? If you can confirm good behavior on the DZ devices and bad on the VH we can explore why... - Mark