Hello,
I am using SQMPMockReaderUI to present the reader icon on the screen for testing payment.
I have noticed sometimes it gets Green when I present this.
Any guidance on why it is turning to green? Is there any specific reason or test case?
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Based on the information you’ve provided, the following documentation will help answer your question:
Additional Documentation
Take a Credit Card Payment
Configure the Reader SDK Sample Application
Take a Cash Payment
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Are you identifying or pairing the reader? That’s when the green lights appear. 
But this is Mock UI and the app was initiated with sandbox app ID so the app can not search for the device, right? I am just presenting UI nothing else.
Also, I am testing in the simulator as of now but also noticed the same Green color in the device
If I don’t do anything for some time then it says:
may be it is due to time out?
The green represents the reader being ready to have the card tapped or inserted in the reader. In production when a payment is indicated a green light will appear on the reader indicating that its ready to accept the card.