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1908FP, DDC/CI Power Control Not Working
This is a very specific question, but it's worth a try.
I am attempting to control this DELL 1908FP via software over the supposed DDC/CI it supports.
In order to do this, one must obtain the Capabilities string of the monitor over C++, then follow this tutorial.
https://msdn.microsoft.com/en-us/library/windows/desktop/dd692982(v=vs.85).aspx
I have done that and will edit this post with it in a minute.
Edit: This is the capabilities string.
(vcp(02 04 05 08 10 12 14(05 06 08 0B) 16 18 1A 52 6C 6E 70 AC AE B2 B6 C0 C6 C8 C9 CA D6 DF)type(LCD)mccs_ver(2.1)asset_eep(32)mpu(1.02))
Now, the Capabilities string claims that it supports D6 which is the Power Mode. In this scenario, I've determined that a **bleep** of 1 is on, and 4 is off. This was determined via ControlMyMonitor from NirSoft by running the app with the monitor on and off.
However, changing the **bleep** Power Mode D6 from 1 to 4 via software methods seems to have no effect, and I can't determine why. Other functionality such as changing the brightness, contast, color, etc seem to work. The Power Mode doesn't for some reason.
I have tried the connection in two ways, one via DisplayPort to DVI, and one with DVI to Analog, both of which yield no results.
Is it possible that early DDC/CI monitors did not support this specific functionality? I'm also running an Asus VB175 which by the look of it is a monitor that came out around the same as the DELL 1908FP. However, the VB175 works fine with the above method.
I recognize that this is a long shot, thanks.
DELL-Chris M
Community Manager
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January 15th, 2018 06:00
According to 1908FP User's Guide page 23, DDC/CI can be enabled in the OSD (On Screen Display) for this 10 year old monitor =
Whether it can then be used by that non-tested software is unknown by Dell.
jetompki
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January 15th, 2018 16:00
Thanks for the reply.
I've concluded that this monitor simply doesn't support a write to that Power Mode address over the DDC/CI connection. It seems the only way to change that address is by a direct press of the power button.
A bit disappointing for my setup, but not the end of the world.
swamped207
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January 16th, 2018 01:00
I'm not familiar with the 1908FP, but some of these older monitors can't process DDC/CI commands in sleep mode. To confirm, try reading the capabilities string when the monitor is in sleep mode (0xD6=4) to see if you get a valid response, or even something simpler like just reading the brightness control (0x10).
If the monitor can't process commands when 0xD6=4, try setting it to 3 or 2 instead of 4, and - long shot - try waking it up with 0xD6=0 instead of 1.