(the following information is also in the AIM4170 manual:)

Because some newer computers don't have RS232 ports, it may be necessary to use an RS232 to USB adapter with the AIM4170. The AIM's RS232 port uses only three wires. Pin 2 is the data from the AIM to the computer, pin 3 is the data from the computer to the AIM and pin 5 is ground. Hardware handshaking is not used. The signal amplitude on the I/O lines (pins 2 and 3) is approximately +/-5V.

If the comm port assigned to the USB adapter is not known, try using the "Find Comm Port" command under the "Setup" menu. This will scan from comm 1 to comm 32 to find which port is working. The comm port assigned to the USB adapter can also be found using the Windows Device Manager: Click Start => Settings => Control panel => System => Hardware => Device Manager.

If there seems to be a problem with the USB adapter, here are some tips for checking it. First, make sure another accessory in the computer or another program is not tying up the comm port. For example, if the AIM program is started two times without closing it the first time, the second copy cannot use the comm port. This can happen when the first AIM window gets hidden behind another window so it's not obvious that it is still active. Also, check the icons at the bottom of the screen to see if another copy of the AIM program may have been minimized.

When the AIM first powers up, it sends out a character string that can be received by any terminal emulation program, such as HyperTerminal. To use HyperTerminal, which is a standard accessory in Windows, click on the Start button in the lower left corner of the Windows desktop. Then, click "Programs" -> "Accessories" -> "Communications" -> "HyperTerminal". Set HyperTerminal for the following parameters:

Baud rate=57600; 8 data bits; 1 stop bit; no parity; echo typed characters locally.

When HyperTerminal is ready, turn on the AIM4170 power. The green LED on the AIM front panel will turn on and the text displayed on the computer terminal is the following (or similar):

Antenna Analyzer AIM4170 from Array Solutions Oct 13, 2006

If this is displayed, it means the data from the AIM to the computer is okay. If the text is not displayed, a scope or logic probe can be used to check for pulse activity on pin 2 of the RS232 connector with the PC cable disconnected. Pin 5 of this connector is the Ground pin. The normal voltage at pin 2 is about -5V and it pulses to about +5V several times during a 1 second interval while the text string is output right after the power is turned on. The PC doesn't have to be present at all, so this output test is completely independent of the PC or the operating system.

To check data from the computer to the AIM, type K1 (K and a one). Note the K is upper case. The command K1 will cause the AIM to turn on its Red LED. There is no character space between the K followed by a 1, but the time interval between typing the K and the 1 is not critical. Then, type K0 (K followed by a zero). The Red LED should go off. This indicates the AIM is able to receive commands from the computer; therefore, the I/O data link is working properly.

Recently a problem has been found where Windows does not properly keep track of which comm port is in use. Some problems with the comm port can be solved by removing the port numbers that have been assigned in the past but which are no longer in use. This link has information for cleaning up the port assignments.