The IMPULSE 4000 firmware requires the display screen to be at the home-screen in order for communications to be established. On the IMPULSE 4000, press the ESC button (middle right on control panel) until the display shows IMPULSE 4000 MAIN MENU PAGE 1: Then run the test template. If you have other problems it is likely a loose or misconnected RS232 serial communications cable or an incorrect COM port selection on your computer.
This generally applies to all Ansur-compatible test devices. Be sure that the display menu is at the home position on the compatible test device.