PVI 23TL, 28TL Installation and Operation Manual (Rev J)
DOCR-070365-J
Page
34
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66
7.1 Modbus (RS-485) Network Connections with External Monitoring Systems
The PVI 23-28TL inverter can be connected to an external Data Acquisition System (DAS) via Modbus (RS-
485) connection as shown in figure 7.2.
Figure 7.2 - PVI 23-28TL Inverters in a Modbus (RS-485) Daisy Chain Connected to an External
DAS
When connected to an external Data Acquisition System (DAS), Solectria PVI 23-28TL inverters
support up to 32 inverters/devices on the Modbus (RS-485) daisy chain. The Inverter Modbus IDs are
configurable from 1 to 128.
Solectria recommends that the Modbus (RS-485) daisy chain for PVI 23-28TL inverters is limited to a
maximum length of 1600 ft. (500m).
Care must be taken when daisy chaining the inverters as shown above, utilizing a Shielded Twisted
Pair Modbus cable such as Belden 9841.
The shield continuity should be maintained for the entire length of the daisy chain and should only
be connected to ground (GND) at the Data Acquisition System (DAS). The shield should not be
connected to any of the inverters to prevent any possible ground loops.
It is important to terminate the Modbus (RS-485) bus correctly to minimize any noise and reflections.
The bus should be terminated at the source (the DAS) and at the last Modbus device in the daisy
chain, typically an inverter. The PVI 23-28TL Modbus termination is turned on by flipping switch S402
to the ON position as shown in Table 7.1 should always be left in the off position except for the last
inverter in the daisy chain.
