Data Flow Systems TCU800, Installation And Operation Manual

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C h a p t e r 8
Figure 6
RS-485 Serial Settings
As a Modbus master device, the TCU can communicate with Modbus slave devices at 1200-9600 baud using either ASCII
or TRU protocol. The baud rate and protocol selected for your installation must me identified in the TCU’s configuration.
The protocol options are:
Protocol Data Bits Parity
Option 1 ASCII 7 No
Option 2
ASCII 7 Even
Option 3
ASCII 7 Odd
Option 4 RTU 8 No
Option 5
RTU 8 Even
Option 6 RTU 8 Odd
Wiring an RS-485 Slave Device
The TCU’s P4 connector is its interface to RS-485 devices. Refer to the pin definitions for the TCU’s Bottom Connector 2:
P4 provided on page 8. A wiring diagram is provided below.
The TCU does not support:
15 Force Multiple Coils (control multiple control registers)
16 Preset Multiple Registers (control multiple analog control registers)
TCU as a Modbus Master Device (RS-485 Interface
When the TCU is used as a fixed-speed pump controller, it can poll modbus slave devices and place their register data in
the TCU’s unused registers. Modbus polling is activated by entering the Modbus information (address and length) into the
TCU’s configuration registers. The TCU will then poll the device(s) automatically.