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5.2
Half Duplex .................................................................................................. 23
5.2.1
Timing Diagrams ..................................................................................... 23
5.3
Sample Configurations ................................................................................. 26
5.3.1
Full Duplex Back-to-Back Modems ......................................................... 26
5.3.2
Full Duplex Constant Carrier Master ....................................................... 26
5.3.3
Half Duplex Slave for Constant Carrier Master ....................................... 27
5.3.4
Half Duplex Master Or Slave .................................................................. 28
5.3.5
High Speed Connection to TeleSAFE RTU ............................................ 28
5.3.6
Normal Speed Connection to TeleSAFE RTU ........................................ 29
5.4
System Configuration Procedures ............................................................... 30
5.4.1
Full Duplex Point-to-Point Systems ........................................................ 31
5.4.2
Half Duplex Multi-Point Systems ............................................................ 31
5.5
Common Problems and Solutions ............................................................... 33
5.5.1
RTS Always On in Half Duplex ............................................................... 33
5.5.2
High Error Rate ....................................................................................... 33
5.5.3
Modem Receives Data but Never Transmits .......................................... 34
5.5.4
Other Modems Do Not Receive Data ..................................................... 34
5.5.5
Bad Data at Start of Message................................................................. 34
5.5.6
Bad Data after End of Message ............................................................. 34
5.5.7
Missing End of Long Message ................................................................ 35
5.5.8
RS LED Always On; All Other LEDs Off. ................................................ 35
5.5.9
DTE Transmits Too Soon after Receive ................................................. 35
5.5.10
CD LED Always On in Master Modem .................................................... 35
5.5.11
CD LED Always On in Radio System ..................................................... 36
5.5.12
CD LED Always On in 2 Wire System .................................................... 36
5.6
LED Indicators ............................................................................................. 36
5.7
F Option ....................................................................................................... 37
5.7.1
Supported Communication Parameters .................................................. 37
5.8
M Option ...................................................................................................... 38
5.8.1
Carrier Turn Off and the Modbus RTU Protocol ..................................... 38
5.8.2
M Option Operation ................................................................................ 38
6
MAINTENANCE ........................................................................................... 40
6.1
Gain Adjustments ......................................................................................... 40
6.1.1
Transmitter Adjustment .......................................................................... 40
6.1.2
Receiver Adjustment ............................................................................... 40
6.2
Modem Test Modes ..................................................................................... 40
5902 Bell 202 Modem Hardware Manual
October 19, 2007
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