Being that I will use this terminal mostly for accessing my VAX 4000, I set it to default to 19200 baud. The other "Setup B" settings are:
1) 0101 2) 0011 3) 0010 4) 1010
So, if you read this post and you are struggling with getting your VT100 to communicate with your computer...
First connect your computer to the terminal. You may need a NULL MODEM adapter (I did not), situations vary. Understand the communications settings your computer or server requires. Make sure your vt100 is in ONLINE mode.
Here is how to adjust the communication parameters:
1. Click SETUP button on the upper-left corner of the keyboard.
2. Click the 5 key (Setup A/B/C toggle) to enter the SETUP B section. "B" is where you do your fine tuning adjustments.
2.5 Change the send and transmit baud rates to match your requirements. Exit setup and try comms. This may be all you have to do. CTRL+s to save.
If after setting baud and you still have strange chars or other issues continue to step 3.
3. Return to setip B. Note the groups of horizontal of numbers at the bottom of the screen. These represent the communications parameters. 0=off, 1=on.
4. Assuming like me you're attempting to connect to a VAX 4000 server (or most other computers that expect a N/8/1 terminal) Change the parameters to match the "setup b" settings I listed above. You set parameters by moving your cursor above the number to be changed and use the 6 key on the keyboard ("Toggle I/O") to switch 1 to 0 or 0 to 1. See link below for manual if you need to research your situation.
5. When done hit CTRL+S to save.
6. Exit by hitting the SETUP key.
VT100 Manual (local mirror from VT100.net)