DPS Telecom NetGuardian 832A G5 User Manual page 79

NetGuardian's NVRAM so they will be saved when the unit is rebooted.
Q. The LAN link LED is green on my NetGuardian, but I can't poll it from my T/Mon.
A. Some routers will not forward packets to an IP address until the MAC address of the destination device has
been registered on the router's Address Resolution Protocol (ARP) table. Enter the IP address of your
gateway and your T/Mon system to the ARP table.
Q. What do the terms "port," "address," "display" and "alarm point" mean?
A. These terms refer to numbers that designate the location of a network alarm, from the most general (a port to
which several devices are connected) to the most specific (an individual alarm sensor).
Port: A number designating a serial port through which a monitoring device collects data.
Address: A number designating a device connected to a port.
Display: A number designating a logical group of 64 alarm points.
Alarm Point: A number designating a contact closure that is activated when an alarm condition occurs. For
example, an alarm point might represent a low oil sensor in a generator or an open/close sensor in a door.
These terms originally referred only to physical things: actual ports, devices, and contact closures. For the
sake of consistency, port-address-display-alarm point terminology has been extended to include purely
logical elements: for example, the NetGuardian reports internal alarms on Port 99, Address 1.
Q. What characteristics of an alarm point can be configured through software? For instance, can point 4
be used to sense an active-low signal, or point 5 to sense a level or a edge?
A. The NetGuardian's standard configuration is for all alarm points to be level-sensed. You cannot use
configuration software to convert alarm points to TTL (edge-sensed) operation. TTL alarm points are a
hardware option that must be specified when you order your NetGuardian. Ordering TTL points for your
NetGuardian does not add to the cost of the unit What you can do with the configuration software is change
any alarm point from "Normal" to "Reversed" operation. Switching to Reversed operation has different
effects, depending on the kind of input connected to the alarm point:
· If the alarm input generates an active-high signal, switching to Reversed operation means the
NetGuardian will declare an alarm in the absence of the active-high signal, creating the practical equivalent
of an active-low alarm.
· If the alarm input generates an active-low signal, switching to Reversed operation means the
NetGuardian will declare an alarm in the absence of the active-low signal, creating the practical equivalent of
an active-high alarm.
· If the alarm input is normally open, switching to Reversed operation converts it to a normally closed
alarm point.
· If the alarm input is normally closed, switching to Reversed operation converts it to a normally open
alarm point.
Q. Every time my NetGuardian starts up, I have to reenter the date and time. How can I get the
NetGuardian to automatically maintain the date and time setting?
A. You have three options for keeping the correct time on your NetGuardian:
Real Time Clock Option: You can order your NetGuardian with the Real Time Clock hardware option.
Once it's set, the Real Time Clock will keep the correct date and time, regardless of reboots.
Network Time Protocol Synchronization: If your NetGuardian has Firmware Version 2.9F or later, you
can configure the unit to automatically synchronize to a Network Time Protocol (NTP) server.
· To get the latest NetGuardian firmware, sign in to MyDPS at www.dpstelecom.com/mydps.
· For instructions on configuring your NetGuardian to use NTP synchronization, see your NGEditG5 or
NetGuardian Web Browser Interface user manual.
T/Mon RTU Time Sync Signal: You can configure your T/Mon NOC to send an RTU Time Sync signal at
a regular interval, which you can set to any time period between 10 and 10,080 minutes. The Time Sync will
automatically synchronize the NetGuardian's clock to the T/Mon's clock. And if you set your T/Mon to NTP
synchronization, you'll make sure you have consistent, accurate time stamps throughout your monitoring
network.
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