Data Flow Systems TCU800, Installation And Operation Manual

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M o d b u s S u p p o r t
Figure 7
Configuring the TCU to Poll Modbus Slave
Pump Control Process
When using the TCU as a fixed-speed pump controller, you configure the TCU to poll Modbus slave devices using one of
the following methods:
• Through the TCU’s configuration screens
• Via the TCU editor included in WinTRU Test. WinRTU Test is included in the TCU, PCU and SCU Test kit. The Help
files included with WinRTU Test provide details on configuring the TCU for Modbus polling.
The TCU polls Modbus registers as follows:
Digital Status (10001-19999) and Analog Status (30001-
39999) Registers are polled continually
Digital Control (0001-9999) and Analog Control (40001-
49999) Registers are updated using the multiple register update
command. At TCU power up, the status of the Control
registers is read once.
After TCU power up, Modbus control registers are updated whenever the corresponding TCU registers are changed via
telemetry. Similarly, when Modbus status registers change, their corresponding TCU registers are updated. One module of
Modbus data is processed approximately every 2 seconds.