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6.12 MODBUS CONNECTIONS
For connection of multiple slaves to J1 and/or J2 Modbus SPU3 master input, following
“multidrop” connection and settings need to be taken into account.
Figure 9
–
Multidrop connection diagram
The connection loop needs to be “closed” with termination resistors.
In example Figure 9 the termination resistor needs to be placed at the first device (SPU3/master) and
at the last connected device (slave n).
Figure 10
– Termination resistor switch
The SPU3 termination resistor can be set by way of a jumper switch
in “on”-position.
The termination resistor of the last device depends on the device. This can be done using a
resistor or by way of a switch. Please contact your supplier.
NOTE:
Do not connect the signal ground to the ship hull.
Termination resistor switches.
Set the switch in “on”-position to activate
the termination resistor for the
corresponding connection.