American Fibertek RTM-1485-2F8 - Manual (Page 7)

7
RTM-1485-2F8 STATUS INDICATORS
The RTM-1485-2F8 transmitter provides the following LED status indicators to aid in installation
and troubleshooting:
OLI
A bi-color LED indicator monitors the optical input power of the data signal that is being
received at the RTM-1485-2F8 from the MRM-1485-2F8 or the RRM-1485-2F8. DC power and
optical input status associated with this LED are summarized below.
Optical Level Indicator DC Power Status Optical Status
Green On Proper Optical Input Power Present
Red On Optical Input Not Detected
Off Off Check Power Supply
VLI
A bi-color LED indicator is provided for the video input to the RTM-1485-2F8. Video status
associated with this LED is summarized below.
Video Presence LED Video Status
Green Proper Input Video Present
Red Input Video Not Detected
DATA TX
A red LED indicator is provided to monitor the RS485 input data from the electrical interface,
through the RTM-1485-2F8, and out onto the fiber. The intensity of this indicator will vary with
input data patterns, however in typical applications it will cycle on and off as data is transmitted.
RS485 status associated with this LED is summarized below.
DATA TX LED RS485 Status
Red Data Flow Present
Off Data Flow Not Detected
DATA RX
A red LED indicator is provided to monitor the RS485 data coming in from the fiber, through the
RTM-1485-2F8, and out onto the electrical interface. The intensity of this indicator will vary with
input data patterns, however in typical applications it will cycle on and off as data is received.
RS485 status associated with this LED is summarized below.
DATA RX LED RS485 Status
Red Data Flow Present
Off Data Flow Not Detected
RS485 TERMINATIONS
The RS485 protocol is an expanded version of the original RS422 protocol. The RS485 protocol
is an expanded version of the original RS422 protocol. RS485 differs from RS422 in the ability
of the transmitter devices to go into a high impedance (Hi-Z) state. This allows multiple
transmitter devices to reside on the same wire pair. The software must dictate a protocol that
allows one device to transmit at any one time to prevent data crashes. Data wiring can use two
wires or four wires. Using two wires the system works in half duplex. This means that data is
exchanged between two points sequentially. When a four-wire system is used, the system may
be full duplex. In many cases the system head end controller will continuously poll data from all
remote devices. The remote devices all respond back to the head end (one at a time!) as they
are addressed. This property of the network rests solely in the hands of the software or
firmware.