Use RS232 and GPIB are available, if your demand of testing velocity is not harsh, that you can use RS232, it will save your money.
From your mentioning that your test station is easy, you can use "relay array (hardware)" to do the test motion. if you cann't make a digital hardware which controls the relay open or close. that you can purchase NI products, PCI-6601 or PCI6024.....to do the action.