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