User's Manual

EP308 SpecificationsManual
06E00079-001A
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EP308 SpecificationsManual | Trapeze July 22, 20144
Figure 8-1
Note: C1 and C2 are 0
Caution: An RS-485 specified termination uses a 100 ohm resistors external to each node at
each end of the bus which if installed in a J1708 system can cause the network to fail.
8.2 RS232
The minimum/maximum voltages on the bus are specified to be +/-15V. A ‘0’ is +5 to +15V and
a ‘1’ is -5 to -15V. Voltages between -3V and +3V are undefined by the standard. The limiting
factor for line length is the maximum allowable capacitance of 2500 pF. This limits the wire
length to 15m (50ft).
8.2.1 12V Systems
Maximum voltages: -3 to +16V with the bus idle
8.2.2 24V Systems
Maximum voltages: -3 to +32V with the bus idle