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MODEL 420
TELEBYTE TECHNOLOGY, INC.
MODEL 420
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Modem Type
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Data (synchronous)
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Maximum Data Rate
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128Kbps
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Data Bus
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External
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Data Modulation Protocol
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Proprietary
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CONNECTIONS
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Purpose
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Location
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Purpose
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Location
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DC power
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CN1
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Receive
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CN4
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RS-232/422
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CN2
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Transmit
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CN5
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Ground
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CN3
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CARRIER ON
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Setting
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SW2/C
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» Always on
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On
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RTS high
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Off
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GROUND
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Setting
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JP1
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» Frame and signal ground connected
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Pins 1 & 2 closed
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Frame and signal ground separate
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Pins 3 & 4 closed
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IMPEDANCE
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Setting
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JP2
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» 135 Ohms(low)
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Pins 1 & 4 closed
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High
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Pins 3 & 4 closed
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LINE SPEED
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Speed
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SW1/A
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SW1/B
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SW1/C
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SW1/D
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SW1/E
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SW1/F
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32Kbps
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Up
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Down
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Down
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Down
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Down
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Down
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48Kbps
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Down
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Up
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Down
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Down
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Down
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Down
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56Kbps
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Down
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Down
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Up
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Down
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Down
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Down
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» 64Kbps
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Down
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Down
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Down
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Up
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Down
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Down
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72Kbps
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Down
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Down
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Down
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Down
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Up
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Down
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128Kbps
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Down
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Down
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Down
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Down
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Down
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Up
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RECEIVE CLOCK
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Setting
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SW/H
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» Disabled
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Down
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Enabled
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Up
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RTS/CTS DELAY
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Setting
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SW2/A
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SW2/B
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» Disabled
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Off
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Off
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7ms
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On
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Off
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60ms
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Off
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On
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TRANSMIT CLOCK SOURCE
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Setting
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SW1/G
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» Internal
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Down
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External
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Up
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FACTORY CONFIGURED SETTINGS
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Jumper
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Setting
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SW2/D
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Not used
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DIAGNOSTIC LED(S)
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LED
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Color
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Status
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Condition
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PWR
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Red
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On
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Power is on
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PWR
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Red
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Off
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Power is off
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TD
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Red
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On
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Modem is transmitting data
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TD
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Red
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Off
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Modem is not transmitting data
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RD
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Red
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On
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Modem is receiving data
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RD
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Red
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Off
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Modem is not receiving data
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RTS
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Red
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On
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RTS signal is high
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RTS
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Red
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Off
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RTS signal is low
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DCD
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Red
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On
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Carrier signal detected
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DCD
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Red
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Off
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Carrier signal not detected
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TM
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Red
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On
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Modem is in test mode
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TM
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Red
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Off
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Modem is in test mode
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