My credit card software says that the card data is invalid

Cause : The Card Reader's transmit speed is too fast.

Solution: Slow down the transmit speed on the reader. Use Windows notepad to repeatedly swipe credit cards to verify that the data is received the same, each time the card is read.

Steps: After downloading and installing the Universal Programmer software you will want to run it and follow the steps below:

Press F1 to display the Interface settings dialog.
Use the Tab key or the mouse to position the cursor over the Transmit Speed settings
At this point you can simply type in the new transmit speed, higher is slower, or use the up down arrows on the window to change it
Once you get the Transmit speed set to the setting you desire Click on the Ok button to save in memory.
If the software does not prompt you to send the configuration to the reader you may click on the Send button on the Toolbar or you may choose the Send Configuration option from the File menu. The reader will beep and you will see a progress bar run across the window indicating that the configuration is being sent to the reader.
Test your card output in Windows notepad, if this did not fix the issue then repeat Steps 1 through 4 but increase the transmit speed value each time.