Product data

16
Networking Hardware
2.2.14 PLC (Programmable Logic Controller) (supporting MODBUS
TM
)
Programmable Logic Controllers can be used as master devices on EIA-485 networks. When
multiple controllers are connected over an EIA-485 bus, they are not able to communicate with
each other. However, a master device, such as a PLC or PC, is able to poll each controller and
retrieve information.
Morningstar controllers are MODBUS
TM
RTU (remote terminal unit) slave devices and can be
polled by RTUs and PLCs with MODBUS
TM
capability. SCADA (System Control And Data Acquisi-
tion) systems often use PLCs to poll RTU devices for data.
PLCs vary greatly in their features and pricing, however, you must be sure the PLC is MOD-
BUS
TM
compatible for it to communicate with Morningstar products.