1275T / 1285T Series
Digital Clock Display
INSTALLATION
Revision 1.0
Page - 5
Note the following cabling information for this wiring guide:
•
Only two pairs of wires are used in the 8-pin RJ 45 connector to carry Ethernet signals.
•
Even though pins 4, 5, 7 and 8 are not used, it is mandatory that they be present in the cable.
•
10BaseT and 100BaseT use the same pins, a crossover cable made for one will also work with the
other.
•
Pairs may be solid colours and not have a stripe.
•
Category 5 cable must use Category 5 rated connectors.
The maximum cable run between the 1275T/1285T and the supporting hub is 300 ft (90 m). The
maximum combined cable run between any two end points (i.e. 1275T/1285T and PC/laptop via
network hub) is 675 feet (205 m).
Devices on the Ethernet network continually monitor the receive data path for activity as a means of
checking that the link is working correctly. When the network is idle, the devices also send a link test
signal to one another to verify link integrity. The 1275T/1285T rear panel is fitted with two LEDs to
monitor the Ethernet connection.
10/100
This Amber LED is ON when a 100Base-TX link is last detected. The LED is OFF when a 10Base-T
link is last detected (the LINK LED is ON). Upon power-up the LED is OFF as the last detected rate is
not known and therefore defaults to the 10Base-T state until rate detection is completed.
LN/AC
This dual purpose Green LED indicates that the 1275T/1285T has established a valid link to its hub,
and whether the 1275T/1285T is sending or receiving data. This LED will be ON when the
1275T/1285T has established a good link to its supporting hub. This gives you a good indication that
the segment is wired correctly. The LED will BLINK when the 1275T/1285T is sending or receiving
data. The LED will be OFF if there is no valid connection.
2.2.3. Serial Port Connections
COM
This female 9 pin D connector is used for connecting a computer to upload firmware to the
1275T/1285T. It is also used as a diagnostic port for troubleshooting. See section 6 for
information on upgrading the firmware.
Pin #
Name
Description
1
2
TxD
RS-232 Transmit Output
3
RxD
RS-232 Receive Input
4
5
Sig Gnd
RS-232 Signal Ground
6
7
8
9
Table 2-2: COM Port Pinout
