The ddcprobe command is a utility that can be used to retrieve information about the display device connected to a computer running Linux. It can be used to find out the monitor's vertical refresh rate (VertRefresh) and horizontal sync rate (HorizSync) by querying the display data channel (DDC) of the monitor.
To use ddcprobe, simply type the command followed by the name of the display device (e.g. /dev/ttyS0) at the command prompt:
ddcprobe /dev/ttyS0
This will display the monitor's VertRefresh and HorizSync values, as well as other information about the display device.
For example, the output might look something like this:
Monitor Information: Manufacturer: NEC Model: MultiSync LCD1765 Serial Number: 12345678 Made in week 16 of 2006 EDID version 1 revision 3 Digital display Maximum image size: 37 cm x 30 cm Gamma: 2.20 Support for the following resolutions: 640 x 480 at 60 Hz 800 x 600 at 60 Hz 1024 x 768 at 60 Hz 1280 x 1024 at 60 Hz 1600 x 1200 at 60 Hz 1440 x 900 at 75 Hz 1680 x 1050 at 60 Hz 1920 x 1080 at 60 Hz Vertical scan range: 50-76 Hz Horizontal scan range: 30-83 kHz
You can also use the -q option to suppress all output except for the VertRefresh and HorizSync values:
ddcprobe -q /dev/ttyS0
This will output only the VertRefresh and HorizSync values, like this:
Vertical scan range: 50-76 Hz Horizontal scan range: 30-83 kHz
For more options and usage examples, you can refer to the ddcprobe man page by typing man ddcprobe at the command prompt.