How does the rate controllers perform ratio control?

The HI 4060 Rate Controller, the HI 1769-FC or the HI 1756-FC regulate the flow rate for an ingredient and can be used in an analog Master/Slave arrangement. The following is an example of a two ingredient ratio metric control system that combines the Analog signal feeding information to the slave using a remote set point input.  The analog signal "in" can consist of 4-20 ma, 0-20 ma, 0-5 VDC, 0-10 VDC and can be provided from a multitude of sources. Each ingredient requires a separate controller; each HI 4060RC, HI 1756-FC or HI 1769-FC only controls a single ingredient.

The HI 4060, HI 1769-FC and the HI 1756-FC can also receive continuous digital rate commands from communications or a ladder logic coordinated programs.

The feed rate of ingredient number one is input to the Master Rate Controller via either the front panel, analog, or communications from the PLC. The percentage of flow for ingredient number two is input to the Slave Rate Controller via either the front panel, analog, or communication from the PLC. Rate changes to the HI 4060 across any communications protocol is not limited.

The Master Rate Controller Analog Output function of the HI4060, HI 1756-FC or HI 1769-FC provides a 4 to 20 milliamp output signal proportional to the actual flow rate of ingredient number one. The Slave Rate Controller function contains a Remote Set point input  utilizing a 4 to 20 milliamp input to cause ingredient number two to track the actual flow rate of ingredient number one.

The Start command is provided to the Master Rate Controller in one of three ways: Front Panel keyboard, Remote Function connector, or communications from the PLC. As ingredient number one starts to flow the Start command is provided to the Slave Rate Controller. The flow rates of both ingredients can be monitored by the PLC. If an Allen-Bradley PLC is used, this data can be continuously transferred via Discrete Transfers or upon requested via Block Transfers.

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