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Setting up Latitude 7480 to Connect to (2) U2717D Monitors Daisy Chained
Equipment, Cable & Settings
- Latitude 7480
- No Docking Station
- (2) U2717D Monitors
- Active HDMI to Display Port Adaptor between Laptop and Monitor #1
- DisplayPort 1.2 cable from Monitor #1 (DisplayPort Out) and Monitor #2 (DisplayPort In)
- Monitor #1 - DisplayPort 1.2 Enabled
- Monitor #2 - DisplayPort 1.2 Disabled and MST is Off
Issues & Symptoms
- Video successfully duplicates between Laptop & Monitor with case open
- Video successfully duplicates between Monitors with case closed
- Laptop Monitor & Monitor #1 recognized by OS and appears in Display Settings in the Intel Graphics Settings
- Monitor #2 not recognized by OS and does not appear in Display Settings in the Intel Graphics Settings
- When I set MST to 'On' on Monitor #1, the screen blanks out and places the monitor into a state where there is no video signal recognized
Oh and to "Chris" with the Dell Social Media Support Team - DisplayPort 1.2 & MST are NOT the same thing. If they are, then why are there two settings that can be enabled/disabled independent of each other.
I would like to see a list of the step by steps instructions from Dell detailing how to configure the monitors to extend across them. After 8 hours of dealing with this, I have yet to see a simple list of Step 1, Step 2, Step 3 etc. The diagram in the U2717D isn't helpful as it assumes that the machine has a Display Port out. It took 8 hours with Dell support to figure out that an active adaptor was needed. There is no mention of that in the owner's manual.
DELL-Chris M
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November 18th, 2017 15:00
MST (Multi Stream Transport) and DP (DisplayPort) 1.2 are synonymous in that they perform the same function. In our first DP daisy chained monitor (U2414H), the OSD (On Screen Display) stated Display Port 1.2, not MST =
In later models, we changed it to MST =
You cannot do a DP MST daisy chain setup if DP 1.2/MST is turned off in the 1st monitor. Because I deal with hundreds of different monitor models, for "most" people, it is just easier to state them together in my instructions. Notice on page 28 of the U2717D User's Guide, it even spells out that the "Graphics Card must be certified to DP1.2 with MST option". Notice how the two are listed together.
You wrote =
Monitor #1 - DisplayPort 1.2 Enabled
Monitor #2 - DisplayPort 1.2 Disabled and MST is Off
There is no mention of this setting in the U2717D User's Guide. I only see MST Off or On in its Menu. So explain how you Enabled/Disabled DisplayPort 1.2.
There is the flaw in your setup =
Active HDMI to Display Port Adapter between Laptop and Monitor #1
You cannot use HDMI as the source video out port even with this active adapter.
To use two monitors in a DP1.2/MST daisy chain, the source video out port on the laptop MUST be either USB Type-C/DP, DP, or Mini-DP. The source video out port can never be HDMI, DVI, or VGA.
This is why the U2717D User's Guide specifically showed pictures of a computer using its DP out port =
This is how you should try setting up =
Latitude 7480 USB Type-C/DP out port --> USB-C to DP cable --> #1 U2717D DP in port (MST On)
#1 U2717D DP out port --> DP to mDP cable --> #2 U2717D mDP in port (MST Off)