I'm guessing the card reader is on the network? Does it have a REST api? I'd consult the documentation in that case, it's usually pretty easy to get started with the examples there and work up to extracting the information you want.
As domenico_perre mentioned, if the reader has or interacts with some sort of database, you could possible utilize the DBX app in order to setup database inputs and ingest that data in splunk. : https://splunkbase.splunk.com/app/2686/
This sort of thing seems to fall under the "Internet of Things" umbrella talked about here : http://www.splunk.com/en_us/solutions/solution-areas/internet-of-things.html
In particular, this software http://info.kepware.com/idf-for-splunk is supposed to be able to interface with Honeywell devices and inject the data out of the box. It costs some amount of money, but has a free demo.
Let us know how it goes!
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