How To Verify You Are Using A Null Modem Cable for Serial Console Access
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How To Verify You Are Using A Null Modem Cable for Serial Console Access


Article ID: 171132


Updated On:


Management Center ProxySG Software - SGOS


For the ProxySG, Advanced Secure Gateway, Content Analysis, Reporter, and Management Center hardware devices, a null model (crossover serial cable) is required for serial console access. For the most part the cable should have been included with the packaging of the device when it was shipped. However, there are times when this cable is misplaced for whatever reason and serial console access is required. 

To use the computer's built-in serial port to communicate with a serial device, and it's difficult to determine if the serial cable is correct, see the solution section below to tell the difference between the two cable types of cables. 



Verify The Cable Type

A null modem cable (crossover cable) should be used when interfacing directly between the computers serial port and the serial port on the Symantec products mentioned above. With null modem cables, the transmitting device's Transmit (TX) signal is sent to the receiving device's Receive (RX) line.  Similarly, the receiving device's transmission line is sent to the communicating device's receiving line.  


The first cable picture below is a Crossover type (null modem) DB9 serial cable that is the correct pinout for the devices. Notice that Pin 2 on one side connects to Pin 3 on the other side:

Correct Pinout:


The next picture below is pinout diagram that shows the incorrect cable to be used, which is a "straight through" serial cable. Notice that Pin 2 connects to Pin 2 on the other side, making this a straight through cable:

Incorrect Pinout:


To connect to the serial console, use the following HyperTerminal settings which is mentioned in the KB, What HyperTerminal settings to use to connect to the serial console. The settings mentioned in that KB are listed below:

BPS: 9600
Data bits: 8
Parity: none
Stop bits: 1
Flow Control: none