The 6270A Pressure Controller's USB port on the back panel can be plugged into a computer and then the 6270A can be communicated with with RS232 communications (or files can be transferred to/from the 6270A like it's an external drive). This works the same on a 2271A, 8270A or 8370A pressure controller also.
1. To use the USB connection for RS232 communications follow this menu path on the 6270A touch screen: Setup --> Instrument Setup --> Remote Port --> USB Setup
Ensure that "Remote IF" is set to Computer and "RS232 Emulation" is set to ON.
If "Remote IF" is set to Terminal then every command to the 6270A would be echoed back to the computer. If "RS232 Emulation" is set to Off then the controller can be seen like a USB memory stick on the computer (transfer saved image files from controller to computer).
Check the baud rate, and other settings on the Remote Port screen by clicking on [RS-232 Setup]. Ensure that Emulation Mode is set to SCPI
With the above settings, when you plug the 6270A into a computer with a USB cable the computer should recognize that a new device is connected and try to load/find the driver for it. If it does not automatically do this, copy the below file named usbser.sys to this path, C:\Windows\System32\drivers and then have Windows search for it again. If Windows doesn't find it, manually direct Windows to this folder.
Then go to Windows Device Manager --> Ports (COM & LPT) and see if a new device is there with an assigned COM port. If it has a yellow alert, try to update the driver file. Here is a view of the 6270A recognized as COM6 by a computer.
2. To use the USB connection for file transfers (screen images saved by the 0 SAVE button), follow this menu path on the 6270A touch screen: Setup --> Instrument Setup --> Remote Port --> USB Setup, and ensure that "RS232 Emulation" is set to OFF.
See this article for the necessary commands to minimally communicate with a 6270A controller by remote commands, 6270A Pressure Controller Setup in COMPASS for Pressure