Table of Contents
Advertisement
Hardware Installation
Revised 2015-07-16
USB Device Cable
USB Device Cable
This is an Ethernet-over-USB connection which behaves like an Ethernet connection. It can be connected to a PC
with all major operating systems. Driver installation and detection should be automatic on a properly configured
OS. If you are connecting to the unit via the USB port, you will need a Type A plug to Mini-B plug USB cable. In
order for the USB connection to work, you need to install the Sixnet USB driver which is available at
www.redlion.net.
USB Host Cable
This port will accept directly mounted devices such as a USB memory stick, wireless adapters, etc. Remote devices
can be connected to by using a USB cable. The end of the cable that connects to the unit must be a standard USB
Type A plug.
Note: No software functions have been defined for this port yet. This functionality will be available in a future
firmware release. Contact Red Lion for expected availability.
Serial RS485 Wiring
RS485 connections are made to screw terminals on the top of the RTU. These terminals provide a RS485 (2-wire,
half duplex only) connection to a network of RS485 devices connected in a bus topology, or a one-one-one con-
nection to another RS485 device. Never connect RS485 devices in a star topology. Five terminals (for signal
ground, voltage bias, termination, 485- and 485+) are provided. Generally, 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 to the RTU will result if incorrectly connected. It is highly recommended that the signal
ground (IGND) is tied to an appropriate ground (if available) between all RS485 units. The signal ground is fully iso-
lated from the P1 and P2 ground and power. 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, the shield to connect the signal
grounds between stations can be used. This is not optimal (especially for long cable runs) but should work in most
situations.
RS485 Termination: The RTU has RS485 termination components (120 ohm resistor and a capacitor connected in
series) already inside. To terminate your RS485 network, tie the "TERM" terminal to the RS485 - terminal. Make
sure to use the same type and size conductor as already used for the RS485 - connection. It is recommended that
both end stations of the RS485 network be terminated. Termination is only needed at the stations on the end-
points of the bus, never terminate any of the other stations between the endpoints. For other 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-float-
ing) 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. The RAM 9000 provides a way to easily connect external biasing resistors if needed. To bias the
RAM 9000 Series Hardware Guide
2-34
Advertisement
Table of Contents
