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ISC Communications
41.12
Configuring Two LNL-838A RS-232 to RS-485 Converters
Use the following information to set up black boxes LNL-838A (LD485A).
41.12.1
Black Box Settings for 2-wire RS-485 Configuration
Jumpers
W5 should be on A-B to set RTS/CTS.
W8 should be on B-C to set 2-wire
W9 should be on C to set 0-msec
W15 should be on B-C to set DATA Enabled
W16 should be on B to set 0.1 msec Turn Around Delay. This may need to
be changed depending on the distance of the RS-485 line. Refer to the
Black Box manual.
W17 should be on D to set 0.15 ms Driver Enable Hold
W19 - NO JUMPER. This is for testing purposes only.
XW1A - Jumper-block must be installed here to set DCE Emulation Mode.
Switches
S1 - Out to set Normal
S2 - ON to set Terminated
S3 - OFF to set Not Biased
ISC
Communication Interface Type: RS-485
RS-485 Type: 2-wire RS-485
Port 1 RS-485 EOL Termination: Termination OFF
41.12.2
Wiring
TxA and RxA must be jumpered together on the terminal strip inside the converter (see diagram). TxB and
RxB must be jumpered together on the terminal strip inside the converter (see diagram).
244 —
revision 7
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