INSTALLATION:
Data Cables
:
The LDM-MR19.2's data-communication connectors (a four-screw terminal block and a DB25 connector) are on its rear panel. The terminal block holds four screws for connecting the Transmit (XMT) and Receive (RCV) telephone lines. The
Transmit and Receive pairs are polarity insensitive. Connect the Transmit pair to the XMT terminals; for 2-wire operation, this is all you need. For 4-wire operation, connect the Receive pair to the RCV terminals. A nut for optional ground
connection is located on the right side of the rear panel.
Setting the Internal Controls
:
After you install the cabling, you'll need to configure the LDM-MR19.2 for your application by setting its internal straps (jumpers) and switches as necessary. To set internal jumpers and switches, follow these steps below.
1. Loosen the screw holding the top cover in place (located at the top of the rear panel.
2. Remove the top cover.
3. Adjust the jumpers and switches for the configuration you want.
4. Replace the top cover and tighten the retaining screw.
OPERATION:
Controls and Indicators:
All of the LDM-MR19.2's external controls and LED indicators are located on the LDM-MR19.2's front panel.
A.
DIG:
Pressing the Digital Loopback button causes the local LDM-MR19.2 to loop received data and clock to its transmitter. Data Set Ready goes low.
B.
ANA:
Pressing the Analog Loopback (V.54 Loop) button causes the local LDM-MR19.2 to loop its transmitter output back to its receiver. This loopback can also be activated from the terminal when the Pin 18 strap is set to EN.
C.
REM
: Pressing The Remote Digital Loopback (V.54 Loop 2) button causes the remote LDM-MR19.2 to loop received data and clock to its transmitter. Data Set Ready goes low. This loopback can also be activated from the terminal when the
Pin 21 strap is set to RLB EN.
1.
PWR:
Green LED is ON when power is present.
2.
RTS:
Yellow LED is ON when DTE activates Request to Send.
3.
TD:
Yellow LED is ON when steady SPACE is being transmitted. It flickers when data is transmitted.
4.
RD:
Yellow LED is ON when steady SPACE is being received. It flickers when data is received.
5.
DCD:
Yellow LED is ON when a valid Receive signal is present.
6.
TEST:
Red LED is ON when the LDM-MR19.2 is in any of the three loopback modes.
Turning the Unit ON:
If you haven't already, plug the LDM-MR19.2's AC power cord into a working AC outlet. The PWR LED should light to indicate that the unit is ON. If the local and remote units are both operating and passing data, the LED's should look like this:
PWR:
ON
TD:
Flashing or OFF
RD:
Flashing or OFF
RTS:
ON or Flashing
DCD:
ON or Flashing
TEST:
OFF
If the LED's don't look like this, make sure none of the three front-panel pushbuttons are pushed in.
Operating Procedure:
The LDM-MR19.2 can operate entirely unattended. However, you should check the unit's LED indicators once in a while to make sure that everything is OK. While the unit is ON, operating personnel are not exposed to voltages in excess of 30
volts on any card or accessible area of the unit's DC power supply. Regardless of this, DO NOT open the unit while it is ON.
Reconfiguration:
If at some point you need to reconfigure the unit to operate differently, with a new data rate or new clock source, for example--you can change the settings of the unit's internal controls. Unplug the unit, then follow the procedure for possible
settings of the controls.
