DATA-LINC GROUP
5
MDL500 User Guide
PN 161-10003-002B
rev 8/03
Field Configuration Procedure
The field configuration procedure is as follows:
1.
Remove the unit’s cover by removing the four screws on top of the modem.
2.
Set the Remote units for either full or half-duplex operation by positioning the jumper on header P4, located behind
the DB25 connector. For full-duplex operation, the jumper should be in the B-C position; for half-duplex, multi-point
operation using RTS line carrier control, the jumper should be in the A-B position.
3. Confirm that the jumpers on locations P1 and P2 are in the B-C position.
4. Replace the cover.
5.
Connect the RS232 communications port of the Data Terminal Equipment (DTE) (PC, PLC, etc.) to the MDL500
unit with an appropriate cable.
6.
Connect the transmission line to the unit at the pluggable terminal block. There is no polarity requirement.
Connect the unit’s power cord to the barrel jack in the rear panel of the modem and plug the modular transformer into a
convenient 120VAC outlet. Plugging the power in will power up the units; there is no “On/Off” switch.
Operation
Point-to-point, full or half-duplex operation is usually conducted with the both the Master and Remote MDL carriers on all the
time. This is achieved by placing the P4 jumper in the B-C position, which causes the MDL to ignore the RTS line.
In half-duplex, multi-drop, operating mode, with the P4 jumper in the A-B position, the RTS line of the intelligent device that a
Remote MDL is connected to (PC, PLC or RTU) is used to control the MDL’s transmitted carrier. When logic low, the carrier
is turned off; when logic high, the carrier is turned on. If the RS232 cable is disconnected, the RTS connection on the MDL is
biased low and the carrier remains off. (If the P4 jumper is in the B-C position, the RTS connection is biased high and the
carrier will stay on.)
When properly configured, the MDL500 is capable of half or full-duplex data transmission at rates up to 9600 baud. MDL’s
require no settings for data rate and will operate transparently as data is fed to them. They will begin communicating data as
soon as connections are made and they are powered up.
