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Product Data Sheet

(LCF) Local Control Function Blocks

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Stand-Alone Control For Remote I/O

Local Control Function Blocks (LCF Blocks) provide a family of over thirty analog and digital functions for applications requiring sequential control and remote set point, closed loop, proportional, and temperature control. Stored in EEPROM in duTec's line of Remote I/O chassis, LCF Blocks perform remote and stand-alone control operations.

Placing both logic and process control in the Remote I/O chassis has several advantages. In small applications, LCF Blocks can eliminate the need for PCs, small PLCs, temperature/process controllers, and relay panels, thus providing a significant cost savings.

In larger systems where the Remote I/O chassis are linked to a host computer, the Remote I/O can now sense a failure in that host or its data link and take corrective action. When a failure is sensed, the LCF Blocks are enabled and 'take control' of their locally connected I/O, thus providing an automatic transfer of control.

duTec's Remote I/O chassis with LCF Blocks can access a maximum of 32 I/O points, 16 of which can be analog. Using duTec's LCF Blocks, it is possible to run multiple process control loops from a single remote node.

LCF Blocks are configured and downloaded to duTec's Remote I/O chassis using an intuitive Windows program. Licensed, but without protection, the program is easy to use and cost effective for multiple applications. duTec Remote I/O products provide complete system solutions, offering over 50 types of analog, digital, temperature and frequency I/O modules which can be mixed in any configuration on the I/O chassis. Each I/O point is fully isolated, module-to-module and module-to-logic, providing a highly reliable I/O network. The I/O PLEXER product line is housed in a stainless steel chassis, each unit containing a local processor board and either AC or DC power supplies ranging from 10VDC to 265VAC. Three expansion chassis can be added, providing an additional 48 digital I/O points per network address.

Features and Benefits


Local Control Function Blocks can be applied in most applications where local control is important for safety, increased control or cost savings. Using LCF Blocks, logic, set-point, temperature and process control operations are now controllable from duTec Remote I/O chassis.

In addition to providing stand-alone and backup control, the use of LCF Blocks can minimize host computational load and communications circuit traffic.

Pump control, level control, high-high/low-low alarms, and most remote RTU applications can be addressed using duTec's Local Control Function Blocks.


Local Control Function Blocks are provided as a standard feature with the following duTec Remote I/O Chassis: BASIC I/OADs, I/O PLEXERs, and I/O PLEXER Repeaters. In addition to LCF Blocks, all duTec Remote I/O products support the duTec expanded Optomux instruction set. A table of Local Control Function Blocks is shown below.

AND / NAND Gates

Or / NOR Gates



2 Input AND/NAND
3 Input AND/NAND
4 Input AND/NAND

2 Input OR/NOR
3 Input OR/NOR
4 Input OR/NOR
2 Input XOR/XNOR

A < B
A > B
A = B

A <= B
A >= B
A <> B


  • Dead-band

  • Multi-band


  • Proportional

  • Temperature

  •  PID

Latches State Machine



Digital Latch
D-flip flop
Analog Sample & Hold

Truth Table
(max. 4 In/4 Out)

A + B
A - B

Avg A and B
Max of A or B
Min of A or B

Pulse Width Modulation

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