I have a desktop application written in Python.
I am using Create Checkout API to send amount to the Flex Terminal. It’s working fine and I am able to generate custom receipts.
I would like to get the signature customer draws on the terminal screen in case of credit card payments. Is there an API to return signature image?
Unfortunately there isn’t an API that will return the signature image of a payment. 
One thing I noticed, the terminal does give option to sign all the time. Is the functionality tied to the amount?
In what cases are you not seeing the Terminal ask for the amount? I believe there is a setting where the amount will determine whether or not the checkout asks for a signature.