User manual

Toolbox 32 User Manual 1.47d www.cse-semaphore.com/mykingfisher

Page

Ladder Logic - Overview

Ladder Logic is used to add intelligence to the RTU. It can be programmed to monitor inputs, control outputs

and communicate with other RTUs or devices.

Input Blocks

Output Blocks

• Ladder Logic is a series of logic blocks arranged in the shape of a physical ladder

• Blocks are processed from left to right and from top to bottom

• Ladder logic blocks are configured on pages. Each page can have up to 7 lines (or rungs) of ladder logic.

• Ladder logic can be processed up to 300 times per second (depending on how busy the RTU is)

• Each ladder rung is either logically true or false

• Ladder rungs have 5 input blocks (contacts) and 1 output block (coil)

• Input blocks are used to check if something is True or False eg. is a register too high?

• Output blocks are used to do something eg. Set a value in a register or send a message

• Multiple rungs can be linked together to trigger one or more output blocks

• An output block is processed whenever a rung of input blocks are logically true and are connected to the

output block

• If all paths to an output block are logically false, the output block is ignored and the next rung is

processed

Multiple Ladder Files

Up to 16 ladder logic files (Filename.LL) can be added to each RTU site by using Project, Add A Site Or

Logic File and then selecting the additional ladder file. All the ladder logic files can then be compiled into a

single output file by selecting the site's SDB window and selecting Logic, Compile. An LLO file will be

generated that has the same name as the RTU site and is now ready for downloading. Multiple ladder files

are commonly used when using function blocks.

• Note 1: Please ensure that each ladder logic file is saved before compiling otherwise any unsaved

changes will not be included in the compiled output file.

• Note 2: Multiple ladders are compiled in the order that they are added to the RTU site. The top ladder is

compiled first. The order may be changed by editing the project file (filename.PRJ) using a text editor or

by deleting the logic files and adding them again to the project.

• Note 3: Ladder logic defined after the first function block will not be regularly scanned. When adding a

logic file containing function blocks to Filename.SDB, ensure that the logic file appears under

Filename.LL in the project window.