We currently need to create a C# DLL that can be used within VFP to communicate (i.e. send/receive) with an Ingenico 6550 pin pad. I've tried a couple of the different C# open source USBHID libs out there, but we cannot get this to work reliably all the time. Some message sends work and others don't. Some responses come back from the device fine and others don't.

Needless to say, Ingenico's test RBA app works flawlessly when communicating with the device, but I don't know what language or API they are using.

I was wondering if anyone could please point me to either a working sample app with source, another working C# lib, or some useful information that would help in successfully coding.

Thanks.