Advertisement
BAUD RATE SETTINGS (SWITCHES 4 AND 5)
BAUD
Switch 4, Position
RATE
1
2
3
4
(bps)
1200
ON
OFF OFF
ON
2400
ON
ON
ON
OFF
4800
ON
ON
OFF OFF
9600
ON
OFF OFF OFF
19200
OFF OFF OFF OFF
38400
OFF OFF OFF OFF
56000
OFF OFF OFF OFF
64000
OFF OFF OFF OFF
112000
OFF OFF OFF OFF
128000
OFF OFF OFF OFF
TRANSMIT CLOCK OPTIONS (Switch 6)
Switch 6, Position
Pin 15
Clock Source
1
2
3
Internal
OFF
ON
OFF
ON
Recovered
ON
OFF OFF
ON
External
OFF OFF
ON
ON
Pin 15
-
-
OFF
Disabled
Switch 5, Position
1
2
3
4
5
ON
OFF
ON
ON
ON
ON
OFF OFF
ON
ON
ON
OFF OFF
ON
ON
ON
OFF OFF
ON
ON
ON
OFF OFF
ON
ON
OFF OFF
ON
OFF
ON
OFF
ON
OFF OFF
ON
OFF
ON
OFF OFF
ON
ON
OFF OFF OFF
ON
OFF
ON
OFF OFF OFF
To achieve a Master Clock, one of the Line
4
Drivers should be set to internal or external
clocking and the other Line Driver(s) set to
recovered clock.
-
Node Termination:
The user can select whether or not the termination network for the receiver is connected to the line.
Terminating the devices on the extreme ends of the line reduces distortion and improves overall signal quality in
most applications. The factory setting is with Switch 7 in the TERM position.
6
7
8
In Point-to-Point applications, both devices should have the node termination option enabled.
In multipoint applications, only the two devices at the extreme ends of the line should be terminated. Configuring
ON
ON
ON
any of the other devices on the line for node termination would result in an increase in the amount of distortion and
possible data errors.
OFF
ON
ON
Jumpers:
OFF
ON
ON
Four options are user-configurable via internal jumpers:
1. Constant Carrier/Switched Mode-Jumper W2
OFF
ON
ON
2. RTS/CTS Delay (for Switched Mode)-Jumper W2
3. Full/Half Duplex-Jumper W3
OFF
ON
ON
4. Frame Ground/Signal Ground-Jumper W1
OFF
ON
ON
Constant Carrier or Switched Mode:
Jumper W2 is used to select Constant Carrier or Switched Mode. This option determines the use of the
ON
ON
ON
Request to Send signal, with selection dependent on your particular application. When the jumper block is in the
Constant Carrier position, Constant Carrier Mode is selected. If Switched Mode is desired, the jumper block would
OFF
ON
ON
be placed in one of the four RTS/CTS delay positions.
ON
OFF
ON
In Constant Carrier Mode, the unit functions as if RTS is constantly asserted. The EIA 485 transmitter is
ON
ON
OFF
always on, and the unit CTS signal remains high. Any data sent by the attached RS-232 device is automatically
transmitted by the Line Driver. The RTS LED on the unit's front panel will always be on, and the CD indicator of the
remote Line Driver(s) will remain lit. Constant Carrier Mode is most commonly used in multipoint applications that
have a "master" device communicating with two or more "slaves". The master DTE is configured for Constant
Carrier Mode, while the slave devices are set to Switched Mode.
In Switched Mode, the Line Driver's transmitter isn't activated until the DTE device asserts RTS. (Unlike
Constant Carrier Mode, RTS is not held in a pseudo-asserted state). When the attached DTE device raises RTS,
the Line Driver's RTS LED will light. The remote unit's CD LED will light, indicating that a transmission link has
been established. Once the device drops RTS, the RTS and remote CD lights will go out.
RTS/CTS Delay:
If desired, the user can have a delay inserted after the RS-232 device raises RTS. It will delay the return of
CTS from the Line Driver to the DTE. This feature is useful in applications that require time for the remote driver's
Carrier Detect (CD) signal to activate the link between both RS-232 devices before CTS is raised. If CD hasn't
been asserted before CTS, the link is considered inactive and data transmission should not be attempted by the
attached DTE.
In half duplex operation, the RTS/CTS delay is useful because it allows time to establish which Line Driver will
have control of the line to transmit data
Full or Half-Duplex Operation:
This jumper allows you to select 2- or 4-wire operation. The factory setting is full duplex.
NOTE:
Constant Carrier Mode pertains to full duplex or simplex
operation only. Half duplex does not apply since the RTS
signal is constantly held high in this mode, preventing any
other signals from being raised in the sequential fashion
required by half duplex operation.
NOTE:
RTS/CTS delay applies to Switched Mode ONLY.
Advertisement
