Using a keypad challenge — control program sends to the swipe-card reader

In the case where Control is sending data to Swipe, in conjunction with a keypad challenge, we have the following steps:

  1. Control sends to Swipe.
  2. Swipe replies with, "OK, event primed."
  3. A big delay occurs until the next person swipes their card.
  4. Swipe uses a pulse to say, "I have data available."
  5. Control sends a message, "What is your data?"
  6. Swipe replies with, "Swipe card ID # xxxx was swiped."
  7. Control sends message, "Challenge the user with YYYY."
  8. Swipe replies with, "OK, challenge in progress."
  9. A delay occurs while the user types in the response.
  10. Swipe sends a pulse to Control with, "Challenge complete." (We're assuming that the challenge response doesn't fit in a pulse.)
  11. Control sends a message, "What is the challenge response?"
  12. Swipe replies with, "Challenge response is IZZY."
  13. Control sends a message, "change LED to GREEN."
  14. Swipe replies with, "OK."
  15. A 20-second delay occurs, while the door is opened.
  16. Control sends a message, "Change LED to RED."
  17. Swipe replies with, "OK."

In this case, there were two pulses and six messages. Again, the initial priming message could be discounted.