User`s manual

Electrical Surge and Power Protection
Lightning, electrical surges, and power fluctuations can damage your equipment and/or data through the power lines and/or
the serial data lines. When electrical storms occur, the most effective method of protecting your computer system is to
unplug your computer and peripherals, and disconnect all data and telephone lines.
To protect against lightning, electrical surges, and power fluctuations, Digi recommends uninterruptible power supplies
(UPS), power line filters, and surge protectors for every installation.
A UPS can provide protection from electrical surges and fluctuations in the power supplied to the computer. However, it
does little good to protect the main console if you have no protection on the other devices attached to the system. Power line
filters protect against electrical surges and transient spikes. Some filters even have a shutdown feature that drops power to
the device if voltage drops below a preset level. This prevents the spikes and surges caused by the typical “off and on”
electrical problems that occur during a thunderstorm. AC line filters should be used with all electrical devices connected to
a computer system, no matter how small or simple.
The interface cables themselves present another potential danger. Nearby lightning strikes can induce high-voltage surges
into the cables. Machinery, especially commercial machines with electric motors, often generates electrical noise that can be
picked up by cables and cause data errors or equipment damage. Digi includes SurgeBlock on every SYNC/570i-56.
SurgeBlock clips fast-rising peak voltages to help protect against spikes over twenty-five volts caused by lightning, static, or
induced voltage. For maximum protection we recommend surge suppressors on the peripheral end of all serial cables.
Cables running long distances and/or through electrically noisy areas are subject to noise pickup that can cause data errors
or equipment damage. Destructive power surges can also enter through modems via telephone connections. Filters made
specifically for this purpose should be included on all telephone line connections.
Using a receptacle for only the computer and terminal also protects against data errors or equipment damage. Sharing the
receptacle with noise-producing devices such as fax machines, printers, calculators, and heaters may allow noise pickup.
Grounding Techniques
Many terminals and computers are dependent on earth ground to set a reference for signal ground. Improper grounding or
differences in ground potential between your computer and terminals can damage your equipment or even create a safety
hazard. Consequently, you should make sure that every component in your system is properly grounded.
Connect your computer and all terminals and other peripherals to three-pronged grounded receptacles, making sure that the
receptacles are wired
properly. If you must use three-prong to two-prong adapters, make sure that the adapter ground tabs are properly grounded.
A proper chassis ground guarantees that no dangerous voltages exist on terminal frames. Proper grounding also helps
cancel noise that can otherwise be induced on the frame or equipment.
Local electrical codes may also dictate special grounding arrangements. Your electrician can make sure that your
installation complies with all applicable codes. If you have any doubt about the integrity of the grounding system in your
location, have the system checked by a licensed electrician.
Static Protection
Your computer's case not only houses its family of computer components, but it also protects these sensitive electronic
components from stray magnetic (EMI) and electrical (RFI, static) fields.
WARNING
Using proper static control methods is essential whenever you use, move, or open your computer for modifications.