Monitor Control Command Set
Monitor settings are referred to as Virtual Control Panel (VCP) features. Features are numbered from 0..255, and are specified using the hex representation, e.g. 1A for blue level.
MCCS designates features as being one of three types:
- Continuous (C): Able to take any value up to some maximum
- Non-continuous (NC): Able to take only a designated set of values
- Table (T): Used for "raw" data such as a video LUT
This clean distinction has broken down as the MCCS specification has evolved. Some features have changed category. ddcutil distinguishes between "simple" NC fields, which are encoded using only a single byte (in field SL) and for which there is a simple list of possible values, and "complex" NC fields, where an algorithm must be applied to interpret the bytes of a feature query. This is a ddcutil distinction and not part of the MCCS specification.
Most features are both readable and writable (RW). Some, such as VCP Version (DF), are read-only (RO), while others, such as Restore Factory Defaults (02) are write-only.
- Version 1, September 1998
- Version 2.0, October 1998
Introduced required features Display Controller Type (C8), Display Firmware Level (C9) and VCP Version (DF).
Version 2.1, May 2005
Version 3.0, July 2006
Not upward compatible with Version 2.1. Appears not to have achieved industry acceptance. I have not seen any monitors implementing MCCS 3.0.
- Version 2.2, July 2009
A revision to Version 2.1, incorporating most of the new features from Version 3.0 in a manner upwardly compatible with 2.1.
Note that because Version 2.2 was issued after Version 3.0, when ddcutil reports MCCS versions it orders them 1.0, 2.0, 2.1, 3.0, 2.2.
- Version 2.2a, July 2011
Minor revision to Version 2.2.