A user connected both a Mac and a Windows PC to the HDK202-P23, using the device to output to dual monitors.
The HDK202-P23 has HDMI + DisplayPort inputs. Since the Mac does not provide a native DisplayPort interface, the user connected it via a USB-C to DisplayPort adapter into the KVM’s DP input.
During use, the user encountered a consistently reproducible issue:
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When both the Mac and Windows PC were powered on and connected to the KVM, the Mac could only output to one monitor.
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When the Windows PC was powered off or disconnected, the Mac would resume normal operation and output to both monitors.
This indicated that the problem was not with the monitors or the Mac itself, but related to signal handling when multiple hosts were connected simultaneously.
Reproducing the user environment to pinpoint the signal chain After receiving the feedback, we recreated the user’s setup using the same devices:
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Mac → USB-C to DisplayPort adapter → HDK202-P23 (DP input)
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Monitors connected via HDMI output from the KVM
Testing confirmed that the issue was consistently reproducible. Further analysis revealed that the Mac’s display signal underwent multiple conversions along this path:
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USB-C → DisplayPort (external adapter)
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DisplayPort → HDMI (KVM internal conversion)
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HDMI → Monitor
In this multi-stage signal chain, when another host was connected simultaneously, the display signal initialization and recognition process failed, causing one output to not establish correctly.
Firmware optimization: improving signal establishment across multi-level conversion chains Once the issue was understood, the engineering team optimized the firmware’s video link management logic:
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Streamlined DisplayPort input signal detection and initialization
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Improved internal DP → HDMI conversion link establishment
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Enhanced display stability when multiple hosts are connected simultaneously
After optimization, the user was provided with the firmware upgrade. Upon updating, they confirmed that the Mac could reliably output to both monitors while the Windows PC was also connected—completely resolving the issue.
From single feedback to a standard validation scenario This feedback also helped us identify a critical compatibility test scenario: USB-C → DP → KVM internal conversion → HDMI → multi-monitor output
We have officially incorporated this chain into our product testing framework, including:
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Mac USB-C to DP input testing
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DP input + HDMI output conversion stability validation
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Display establishment testing with multiple hosts connected
This validation is now applied to:
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Firmware optimization verification for existing products
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Standard testing processes for future products
Ensuring stable display behavior in complex conversion chains As USB-C, DisplayPort, and HDMI are increasingly mixed in real-world setups, multi-level signal conversion has become common.
Thanks to this real-world feedback, we improved the HDK202-P23’s handling of multi-level conversion signals, ensuring stable operation in complex system configurations. The user’s issue was resolved, and the product’s compatibility boundaries were further strengthened.
