FAQS

FAQ CATEGORIES

• Troubleshooting
• Scripting / Automated Control

TROUBLESHOOTING

Q: Where can I find general system information about my Dualcom?
A:System settings can be obtained under the Setup page on the web interface or the System Settings selection on the telnet/serial interfaces. Additional information about your system, including the unit's MAC address, serial number, and firmware revision, may be obtained through a special page available on the web interface.

To access this special system information page, first login to the Dualcom's web interface in your browser as the system administrator account. Next, append the page happiekats.shtml to the URL (i.e. http://192.168.1.2/happiekats.shtml where 192.168.1.2 is your unit's IP address) and hit Enter. The resulting page will contain the MAC address, serial number, and firmware revision along with other diagnostic information that may be helpful if you need support.

Q: Why is there no power at the outlets?
A: Check to ensure that the input power cord is plugged in and that the outlet indicator lights are on.

Q: Why do my arrow keys not function in Windows 2000 when I run Hyper Terminal?
A: Prior to connecting the DUALCOM/TRICOM directly to the serial port, download the latest updates and fixes for Win2000, WinXP and WinNT at http://www.microsoft.com

Q: Why does the DUALCOM/TRICOM indicate no load when I have my mini hub plugged into one of the outlets?
A: To avoid improper current readings the DUALCOM/TRICOM is designed so that any load lower then 0.1A is considered zero.

Q: I can not connect to the DUALCOM/TRICOM using the serial port.
A: Check settings to ensure that you are connected to the proper COM port and that the settings on the COM port are 19200, 8, none and flow control set to none

Q: The DUALCOM/TRICOM does not appear to be responding to any commands on all the interfaces
A: If for some reason the DUALCOM/TRICOM stops responding a soft reset can be performed by quickly pressing and releasing the reset button located on the right side panel of the DUALCOM/TRICOM indicated by the nut shaped hole.

Q: Is there a way to reset the DUALCOM/TRICOM to default?
A: To reset the TRICOM press and hold the reset button for thirty seconds then release. The reset button is located on the right side of the DUALCOM/TRICOM indicated by a metal finished, screw nut shaped hole. PLEASE NOTE: Returning the unit back to factory default will erase all your settings.

Q: When calling the TRICOM, I immediately get a "Good Bye" and the unit drops my call.
A: Ensure that the phone you are calling from has caller id enabled or change the settings on the TRICOM to allow all callers.

Q: When I try to access the Serial or Telnet menu on a DUALCOM/TRICOM, the Backspace key seems to not work.
A: The Backspace key is sometimes mapped to different ASCII character codes depending on the operating system. If you are experiencing this problem, please try using Ctrl-H instead.

Q: Why does my new Dualcom not respond on the network after I configured it with the same IP address information as the unit it is replacing?
A: Chances are that this is a problem with the network's ARP cache. To optimize the sending of information as quickly as possible, a network device like a switch or router builds an internal list of MAC addresses and their corresponding IP addresses. When you configure your new Dualcom to use an IP address that is already in this list, the router or switch is still using the MAC address for the Dualcom that is being replaced. (For a full explanation of ARP and how it works, visit the Address Resolution Protocol entry on Wikipedia.)

You can test if this is the issue by connecting a laptop directly to the same switch and VLAN as the Dualcom. If you configure a static IP address inside the same subnet as the Dualcom's address and are able to get to the Dualcom's network interface, this is most likely the problem.

There are two solutions to this problem: wait until the network device "forgets" the MAC/IP relationship (usually between 20 and 30 minutes) or force your network device to clear its ARP cache. For further help with either of these, please contact your network administrator or systems vendor as the details are highly specific to your network.

SCRIPTING / AUTOMATED CONTROL

Q: How can I script control of my Dualcom series PDU?
A: The Simple Network Management Protocol (SNMP) is best suited to remotely control and monitor a Dualcom through custom scripts. While the exact implementation of SNMP in your script will depend heavily on the programming language you choose to use, there are several common threads that any SNMP scripting solution has.

First, ensure that the Dualcom is connected to the network and can be reached over Telnet or HTTP.

Second, enable SNMP on the Dualcom. On the HTTP interface, the settings can be found under the Setup tab in a section marked SNMP. The settings you choose will be specific for your network and needs. As a best practice, you should choose two SNMP community strings -- one for reading and one for writing. (The SNMP write community string can be used for reading as well, but for the best security you should have two separate strings and only give out the one for writing when absolutely necessary.) By default, the string public is used for reading and the string private is used for writing.

We highly recommend that you test SNMP access to the Dualcom at this point. There are several free utilities that can be used, including Cyber Switching's CSTools utility available on our Support page. For users who want to perform raw SNMP testing, we recommend the Net-SNMP suite of programs due to its free nature and excellent cross-platform support; you will need to download Cyber Switching's SNMP Management Information Base (MIB) from our Support page to properly interpret the SNMP values sent back.

Once SNMP traffic can be sent and received from the Dualcom, you are now ready to begin scripting. There are two common methodologies used when scripting a Dualcom:

1. External dependency on CSTools
2. Raw SNMP handling in the language itself

CSTools supports batch-mode operation using command line arguments that lends itself quite well to simple scripting. Since CSTools creates a Dualcom-specific facade between the user and SNMP, it is extremely easy to integrate into scripts. However, it does create an external dependency for the script and requires that the script be distributed with a copy of the CSTools executable.

To remove the external dependency on CSTools, the script must therefore provide the needed SNMP functionality itself. Many programming languages have libraries that abstract the raw SNMP calls needed, so please try to use those where possible. For a brief (but incomplete) list of libraries available, see below:

Language	Library
Java	SNMP4J
	Westhawk's SNMP stack
Perl	Net::SNMP
PHP	SNMP functions
Tcl	Scotty

Handling raw SNMP calls inside your script will require an intermediate familiarity with SNMP and the Cyber Switching MIB (see the download link above). To truly remove all external dependencies, make sure you either use the numeric SNMP Object ID (OID) format (1.3.6.1.4.1...) or copy the needed contents from the MIB file into your script.