Verify that a serial cable is correctly fitted between your computer and the unit. The DB9 connection pins use the standard convention of;

Pin 2 Tx (Transmit data)
Pin 3 Rx (Receive data)
Pin 5 Gnd (Ground)

Most computers with a DB9 serial port connector are configured as;
Pin 2 Tx  (Transmit data)
Pin 3 Rx (Receive data)
Pin 5 Gnd (Ground)

Therefore, for the computer to connect properly to the instrument, a null modem cable or null modem adapter is necessary to cross over the Tx and Rx lines, to insure the Tx from one piece of equipment is going to the Rx of the other unit and vice versa.

The serial interface window is displaying garbage when I type a command, and the commands do not work

The usual cause of this symptom is that the settings of the serial port are incorrect, probably the baud rate. The correct settings are;
Baud rate                   57600 (this is the default, but can be changed utilizing menu command A37)
Data Bits                    8
Stop Bits                    1
Parity                          None
Handshaking          None

Before connecting to the Telnet interface it is necessary to set up the unit IP address and Netmask. These can be set by using the Serial Interface and using the menu commands.  Typical settings would be; 192.168.0.19 (the IP address), 255.255.255.0 (the Netmask), 192.168.0.1 (gateway). Alternatively, if the unit is connected to a network with a DHCP (Dynamic Host Communications Protocol) server, the unit can be set to DHCP ON mode and the unit will automatically acquire a network address from the DHCP server. The acquired address can be viewed by typing “help” on the serial interface and the acquired address will be shown next to the command.
Once the IP address/Netmask  has been set up and the unit is connected to a network (or directly to a computer using an Ethernet crossover cable) a hyperterminal (or other telnet interface program) session can be set up using the unit’s network IP address.

Before connecting to the HTTP interface it is necessary to set up the unit IP address and Netmask. These can be set by using the Serial Interface and using the menu commands. Typical settings would be; 192.168.0.19 (the IP address),  255.255.255.0 (the Netmask), and 192.168.0.1 (gateway). Alternatively, if the unit is connected to a network with a DHCP (Dynamic Host Communications Protocol) server, the unit can be set to DHCP ON mode and the unit will automatically acquire a network address from the DHCP server. The acquired address can be viewed by typing “help” on the serial interface and the acquired address will be shown next to the menu command.
Once the IP address/Netmask  has been set up and the unit is connected to a network (or directly to a computer using an Ethernet crossover cable) communications can be established using a standard web browser (e.g. Internet Explorer).

The unit acts as an SNMP agent, using SNMP v1. The unit’s key parameters can be viewed by an SNMP manager, and a subset of them can be also set by the SNMP manager. In addition, the unit sends “traps” to the predefined SNMP manager address. A trap is initiated when the state of the unit changes (e.g. the pulse input on channel A fails). These traps will be received by the SNMP manager on the Trap Ringer Console. Traps are enabled or disabled by menu command.

Before connecting to the SNMP interface it is necessary to set up both the unit IP address and Netmask, and also the SNMP Manager address to which traps are to be sent. These can be set by using the Serial Interface and using the menu commands . Typical settings would be; 192.168.0.19 (the IP address), 255.255.255.0 (the Netmask), 192.168.0.1 (gateway), and  192.168.0.20 (the SNMP Manager IP Address).

Alternatively, if the unit is connected to a network with a DHCP (Dynamic Host Communications Protocol) server, the unit can be set to DHCP mode and the unit will automatically acquire a network address from the DHCP server. The acquired address can be viewed by typing “help” on the serial interface and the acquired address will be shown next to the menu command.

Once the IP address/Netmask  has been set up and the unit is connected to a network (or directly to a computer using an Ethernet crossover cable) communications can be established using a standard SNMP manager software package.

The Fault LED is a summary indication that illuminates if any of the inputs/outputs is in a fault condition.

If the Fault LED is illuminated verify that all inputs are present, and that all outputs are connected, or that unconnected outputs are correctly terminated with a 50 ohm load.

In order to determine whether the unit has initialized, the serial or Telnet pots can be used to more fully determine unit status.

If no LEDs are illuminated it is likely that unit power has failed.

First verify that the AC supply (supplies for redundant power supply units) is (are) present. If the AC supply is present, check the fuses of the unit. There are two inline fuses in each AC power inlet connector. Verify they are okay by using a Resistance meter across the fuse. The resistance should read less than 1 ohm.

If any of the fuses has failed, replace  the failed fuse(s) and reconnect power. If the unit still does not power up it is likely the internal power supply has failed and it will be necessary to return the unit.