Extension Board for MODBUS on SMARTCON Control Unit
DS-ENGLISH-MODBUS-V2.01-2019.05.15
2 Connection
Connecting to a Strand between Devices
Other devices are connected to the bus in front and behind of the new Slave-Device.
Line configuration:
Figure 2:
single channel
Figure 3:
dual channel
Connecting at the End of a Strand, Bus Termination
There is either no device connected to the bus in front or behind of the new Slave-Device.
Line configuration:
Figure 4:
single channel
Figure 5:
dual channel
Bus termination:
MODBUS-RTU has to be terminated on both ends of every strand. Termination can be accomplished through
the termination resistor implemented in your SMARTCON-Device. Bus termination is activated when the re-
spective switch on the connection board is switched to ”ON” as seen in figure 4.
2.2
explosion proof design
Normaly in explosion proof deisgn there is no termination available in the control unit. That means that the bus
termination must be done seperate outside of the control unit.
Optionaly also a bus termination in the control unit is possible, this must be specified by the order.
In this case you can activate the bus termination by connecting the following terminals:
A with AT and B with BT (single channal version) or
A1 with A1T, B1 with B1T, A2 with A2T and B2 with B2T (dual channel version).
ATTENTION: The shield must be connected to the shielding connection clamp (windowcut) -
see Figure 6 or Figure 7
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