ROC364 Instruction Manual
4-10 Communications Cards Rev Jun/05
RAD/PL
RXD
TXD
DTR
DCD
CTS
RTS
RTS
CTS
DCD
DTR
TXD
RXD
RAD/PL
DOC0118A
1ST DECAL
2ND DECAL
COM 1
COM 2
Figure 4-8. Location of LED Identification Decal
4.3.1 Setting Modem Card Jumpers
The Leased-Line and Radio Modem Communications Cards make use of jumpers to select certain
operational modes. These jumpers must be properly positioned for the modem to operate correctly.
Table 4-2 shows the operating modes and the associated jumper positions for the cards. Refer to Figure
4-3 and Figure 4-4 for jumper locations.
The Leased-Line Communications Card is set by default for 2-wire operation. To use it for 4-wire
operation, jumpers P3, P4, and P5 must be placed in the positions indicated in Table 4-2.
The Radio Modem Communications Card uses jumper P6 to enable power control for keying a radio.
The jumper either grounds or isolates the push-to-talk (PTT) return line. Jumper P6 has a default setting
of GND (ground), but it can be set to ISO (isolated) to achieve a floating PTT, if the radio circuit
requires it.
Table 4-2. Jumper Positions for the Modem Cards
Leased-Line Modem Jumpers
Mode
P3 P4 P5
2-Wire (default) 2W 2W 2W
4-Wire 4W 4W 4W
Radio Modem Jumper
Mode
P6 – –
PTT Grounded (default) GND – –
PTT Isolated ISO – –
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