These ports are identical in connection and functionality. A RJ45 female connector is provided
for each. The pin-outs follow the EIA/TIA-561standard (See figures 4-1 and 4-2). A pre-wired
DB9F to RJ45F adapter is included with these units. Use this adapter along with a RJ45 male
to RJ45 male straight-thru wired patch cable (not included) to make a connection between a
com port on your PC (DB9 male) and either Port A or B (RJ45 female). Refer to the Sixnet
Electronic catalog for more information on connecting to other equipment.
This port is found on all units. It provides a RS485 (2-wire, half duplex only) connection to
Sixnet’s RemoteTRAK I/O modules or other equipment. Four terminals (for signal gnd, 485+,
485-, & termination) are provided. Generally, you connect + to + and – to – between units.
However, since there is no standard for RS485 terminal designations you may need to connect
+ to – and – to + in some cases. No damage will result if you connect incorrectly. It is highly
recommended that you tie the signal ground to an appropriate ground (if available) between all
RS485 units. Make sure to use a good quality communication cable with three conductors
(twisted is preferred) plus a shield. To prevent ground loops, the shield should be connected to
chassis ground on only one end of any cable run.
Note: If you have existing wiring that has only two conductors and a shield, you can
use the shield to connect the signal grounds between stations. This is not optimal
(especially for long cable runs) but should work in most situations.
RS485 Termination: All these units have RS485 termination components (150 ohm resistor
and a 0.1 F capacitor connected in series) already inside. To terminate your RS485 network
just tie the “T” terminal to the RS485 – terminal. Make sure to use the same type and size
conductor as used already used for your RS485 – connection. It is recommended that both end
stations of your RS485 network be terminated. Avoid terminating more than two stations.
Refer to the RemoteTRAK I/O User Manual on how to terminate a RemoteTRAK I/O Module.
For 3
rd
party devices, please refer to their user manual for termination instructions.
Bias Resistors: On a RS485 2-wire network, a pair of bias resistors (1K ohm typically)
acting upon the transmit/receive wires may be required. If bias resistors are not present, the
receive inputs on some RS485 devices may react to noise on the floating wires. The bias
resistors will force the transmit/receive wires to a known (non-floating) state when none of the
RS485 devices are transmitting data. Some RS485 devices have bias resistors built-in, and are
enabled through DIP-switch or jumper settings. Make sure there is only one pair of bias
resistors acting upon the network.
Note: If your RS485 network is made up exclusively of Sixnet devices then these bias
resistors are not necessary.