Connector Configurations
Page
A-3
Eagle TX Series AMOS Based Terminal Server Technical Manual, Rev. 01
Alpha Micro uses RJ-45 or DB-9 connectors for RS-232 device connection. The standard maximum
length of RS-232 cables is 50 feet between devices. If you use low-capacity twisted-pair cable you can
extend the length up to 100 feet.
Important Note
The Federal Communications Commission (FCC) has established rules regarding allowable emission
levels of Class A computing devices (ref: Subpart J of Part 15 of FCC Rules). The Alpha Micro systems
to which this manual applies have been determined to be in compliance with the FCC rules. However,
you should be aware that if other devices, such as terminals and printers, are attached to these systems,
even if the devices are attached in accordance with the instructions contained in this manual, the resulting
configuration may not be in compliance with the referenced FCC rules. Corrective measures, if any are
required, are the responsibility of the user. Information on emission levels of peripheral devices should be
obtained from the manufacturer of the device.
CABLE CONSTRUCTION GUIDELINES
If you want to construct your own cables, there are a few things you should keep in mind:
Cable Length
We strongly recommend that RS-232C cables attached to the Eagle TX Series terminal servers use
twisted-pair cable with an overall shield. As you increase the cable length beyond 100 feet, the reliability
of the data signal decreases. If the cables absolutely must be longer than 100 feet, signal conditioning
equipment (for example, a "short haul modem") can improve signal quality.
Cable Type
We recommend you use a twisted paired shielded and jacketed cable. The cable should be rated at least
CMP Level 3, but you can use CMP Level 5 cable for lines longer than 100 feet. Most cities require that
any low voltage communication cable have a CMP (Communication cable Plenum) rating. This type of
cable should comply with your local fire codes for installation in your facility. Using a high quality
twisted paired, overall shielded cable helps minimize electromagnetic interference. Reducing this
interference protects your system from signal noise. It also protects other devices around your Alpha
Micro computer system (such as a TV or radio) from interference radiated by an improperly shielded
system.
RS-232 RJ-45 CONNECTOR SIGNALS
The table below gives pinout information for the RJ-45 ports on the AM-90 card attached to the terminal
server’s main logic board. Pins are numbered from left to right, looking into the port from outside the
computer chassis.
