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Moreover, to minimize the voltage drop on long distance, the terminal
resistance should be higher than the value defined in the ISO 11898-2.
Table 2-4 may be used as a reference.
Table 2-4: Relation between bus cable and length
Bus Length
(meter)
0~40
40~300
300~600
600~1K
Therefore, the GW-7238D module supplies a jumper for users to
connect the terminator resistor or not. If users want to use this terminator
resistor, please open the GW-7238D cover and use the JP3 jumper to
activate the 120Ω terminator resistor built in the system, as in the figure 2-
10. Note that the default setting is active. And about the J3 jumper setting,
please refer the table 2-5.
Figure2-10:XC100 I/O expansion board layout (Rev1.8 / Rev1.9)
GW-7238D J1939 to MBTCP Server / MBRTU Slave Gateway User's Manual (Ver.1.1, May. 2013) ---
Bus Cable Parameters
Length Related
Resistance
(mΩ/m)
70
0.34mm
< 60
0.6mm
< 40
< 20
13
Cross Section
(Type)
0.25(23AWG)~
2
(22AWG)
0.34(22AWG)~
2
(20AWG)
2
0.5~0.6mm
(20AWG)
2
0.75~0.8mm
(18AWG)
Terminal
Resistance
(Ω)
124
(0.1%)
127
(0.1%)
150~300
150~300
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