In-situ Level TROLL 400, Руководство оператора, Страница: 68 / 85

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Power Connections
The Red wire provides power for Modbus and SDI-12 modes. The Brown wire provides power for the 4-20 mA mode. If power
is present on the Brown wire and not on the Red wire, the device enters the 4-20 mA mode automatically and stays in the 4-
20 mode until power is removed from the Brown wire or is applied to the Red wire. The Red wire has priority. If power is
applied to the Red and Brown wires at the same time, the device will operate in Modbus or SDI-12 modes but not in 4-20.
Communication Protocols
The device automatically switches between Modbus and SDI-12 modes depending on which of the two interfaces has
activity. Modbus and SDI-12 cannot be used at the same time. The communication protocol that is currently in use will block
communication on the other.
Win-Situ 5 Software provides options for configuring analog/SDI-12 communications and Modbus communications on the
Tools tab.
For additional information on Modbus and SDI-12 communications, including the SDI-12
commands and Modbus registers, see
www.in-situ.com/Technical_notes
and scroll to the
Communications and Software Technical Notes section.
Redundant Logging
The instrument is capable of internal logging while participating in a Modbus, SDI-12 or analog network. However, Win-Situ 5
Software cannot communicate with the instrument while it is transmitting Modbus, SDI-12, or 4-20 mA analog data, and the
instrument cannot receive or respond to Modbus, SDI-12, or 4-20 mA analog commands while connected to a PC serial port.
If the PLC or data logger loses data, the data that was logged internally on the instrument can be retrieved using Win-Situ 5
Software.
If the PLC or data logger experiences power loss, the instrument will continue to collect data using its internal batteries and
clock.