7
8
S1-3: Reserved
Switch S1-3 is reserved and
must remain in the OFF position.
S1-3
Setting
On
Not a Valid Setting
Off
Default Setting
S1-4: Echo Mode
The setting for switch S1-4 determines whether the Model
1004ABRC echoes data back to the transmitting device (half-duplex
mode only).
S1-4
Setting
On
Echo On
Off
Echo Off
SWITCH SET “S2”
DIP switch S2 is used to configure transmit impedance, and
2-wire/4-wire operations. The summary table below shows the factory
default settings for switch S2. Following the summary table is a
detailed description of each individual switch.
S2-1 and S2-2: “Transmit Off” Impedance
Switches S2-1 and S2-2 are set together to determine whether the
receiving device “sees” the impedance of the Model 1004ABRC’s trans-
mitter as being “high” or “intermediate” when the transmitter is turned
off. The “intermediate” setting is useful in half-duplex environments
where the receiving device does not respond well to the “high” setting.
S2-1
S2-2
Setting
On
On
Intermediate Impedance
Off
Off
High Impedance
S2-3 and S2-4: 2-wire/4-wire Modes
Switches S2-3 and S2-4 are set together to determine whether the
Model 1004ABRC is in 2-wire or 4-wire operating mode. Note: 2-wire
mode is half-duplex only.
S1-2
S1-3
Setting
On
On
2-wire mode
Off
Off
4-wire mode
3.1.2 SWITCH SETTINGS - MODEM “B”
DIP switches S3 and S4 configure short range Modem B on the
Model 1004ABRC front card. The tables below provide an overview of
Modem A switch settings, including factory default settings. Following
each figure is a detailed description of each switch’s function.
SWITCH SET “S3”
DIP switch S3 is used to configure receive impedance, RTS/CTS
delay and “echo” enable/disable. The summary table below shows the
factory default settings for switch S3.
Following the summary table is a detailed description of each individual
switch.
SWITCH S2 SUMMARY TABLE (factory defaults in bold)
Position
Function
ON Position
OFF Position
S2-1*
TX Impedance
Intermediate
High
S2-2*
TX Impedance
Intermediate
High
S2-3*
2-Wire/4-Wire
2-Wire
4-Wire
S2-4*
2-Wire/4-Wire
2-Wire
4-Wire
*Note:
Switches S2-1 and S2-2 must be switched simultaneously.
Switches S2-3 and S2-4 must be switched simultaneously.
SWITCH S3 SUMMARY TABLE (factory defaults in bold)
Position
Function
ON Position
OFF Position
S3-1
RX Impedance
120 Ohm
16K Ohm
S3-2
RTS/CTS Delay
8 msec
No Delay
S3-3
Reserved
-
Default Setting
S3-4
Echo Mode
Echo ON
Echo OFF
