GarettCom 5843HRT User Manual page 7

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
Pin 8 Output Option Switch: (Switch 5B)
Models 5843 and 5844 Links are provided with this switch to allow users who require more drive
current on the TTL output pin (pin 8) to accomplish this. Selections are High or Low. Consideration
should be given that the current value selected is appropriate for the input of the device being
connected to this data channel.
Test Mode Switch:
Models 5843 and 5844 are provided with this switch to allow users who wish to test the fiber
connections of the link with a built in diagnostic mode. This mode sends a 100Hz signal out the transmit
port as well as looping back the copper port (pins 2 and 3) for diagnostic purposes.
Handshaking Switch:
Each Link/Repeater is provided with this switch to easily adapt the device for use where the connected IED
needs to see active electrical levels on certain handshaking pins but does not require full handshaking
implementation.
Simplex Communication:
Transmit only or receive only communications.
Half Duplex Communication:
Sequential transmit and receive communications.
Full Duplex Communication:
Simultaneous transmit and receive communications.
T:
Transmit optical port.
TE:
Diagnostic LED that illuminates when the Link/Repeater is receiving an electrical transmit from its IED.
TO:
Diagnostic LED that illuminates when the Link/Repeater is transmitting a signal optically.
R:
Receive optical port.
RE:
Diagnostic LED that illuminates when the Link/Repeater is delivering a received optical signal electrically to
the IED.
RO:
Diagnostic LED that illuminates when the Link/Repeater is receiving a signal optically.
Optical Budget:
The optical budget is expressed in dB and is the amount of light loss tolerated for communication. The total
distance between two devices that a signal can be transmitted is determined by subtracting all the losses of
the circuit from the optical budget. Various factors in the optical circuit attenuate the light transmission and
must be accounted for to assure a reliable optical circuit. Key factors include cable attenuation (expressed
as dB per unit length), cable aging, and cable fittings (terminations, splitters, etc.).
Non Return to Zero (NRZ):
This type of encoding scheme does not require the voltage potential of each data bit to return to the zero
potential. No clock or timing recovery is provided with this type of communication except in the start and
stop bits usually found on each data word.
Return to Zero (RZ):
This type of encoding scheme requires the voltage potential of each data bit to return to the zero potential.
This allows timing recovery with each bit instead of just the start and stop bits of the data word.
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