User Manual

RPiLDR Ladder Diagram Editor User Manual


A tutorial and reference description.

De Coninck Ivo

Copyright © 2011 - 2015 De Coninck Ivo.

RPiLDR RPi Ladder Diagram Editor (create, build, test, upload a ladderdiaram) for the RPiPLC hardware.

This is a legal agreement (the "Agreement") between you (either an individual or a single entity) and RPiLDR Software.

  1. LICENSE. RPiLDR is a freeware software application. You are allowed to use and share this software for free.
  2. NO WARRANTIES. The software is provided "as is" without warranty of any kind, either express or implied, including, without limitation, the implied warranties of merchantability, fitness for a particular purpose, or non-infringement of third party. The software is provided with all faults and the entire risk as to satisfactory quality, performance, accuracy and effort is with you.
  3. LIMITATION OF LIABILITY. This software is provided "as-is," without any express or implied warranties. In no event shall the author be held liable for any damages arising from the use of this software.

RPiLDR Version 1.1 Copyright (C) 2011 - 2015 RPiLDR Software. All rights reserved.


This version of the manual is intended to describe the version 1.1 of RPiLDR Editor.

Table of Contents


The RPiLDR project welcomes those who want to get more involved. Look at the project website to find out more.
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The RPiLDR Ladder Diagram Editor is designed to allow you to easily prepare a PLC program by simply placing blocks. Ladder logic diagrams, which are in many ways similar to relay logic diagrams, are frequently used to graphically generate programs. When putting together a ladder logic diagram, you should always bear in mind that the symbols in the diagram represent instructions rather than physical contacts. When the instructions in the program are executed, the states of the inputs are monitored. Depending on these states, various outputs are set either High or Low.

When generating a program, it is a good idea to work from left to right and to only start a new row after the current row has been completed. The second point is also necessary because the program checks for empty rows. You should also make a habit of always assigning a particular output only once when generating a PLC program. If the same output is used more than once in a program, this output will be assigned the state that it receives in the last row in which it is located!


Declaration and maximum count for instructions.

-- Input instruction Output instruction Timers Counters Alarms Analog inputs
Declaration I, Q (0-31) M (0-255) Q (0-31) M(0-255) T (0-31) C (0-31) A (0-31) AD (0-31)

Mnemonic for instructions.

-- Positive Transition Negative Transition Counters Timers Alarms Analog Inputs Alarms

Maximum count for instructions in Ladder Diagram Editor, Simulator and RPiPLC hardware.

--- Mnemonic Ladder Editor Simulator RPiPLC hardware RPiPLC Mnemonic
Inputs I 32 32 64 ?
Outputs Q 32 32 64 ?
Memory M 255 - 255 ?
Timers T 32 - 32 ?
Counters C 32 - 32 ?
Alarms A 32 - 32 ?
Analog inputs AD 32 - 32 ?

Maximum row and columns count for the Ladder Diagram Editor.

Maximum count Count
Rows 100
Columns 10

Ladder DiagramTutorial

The RPiLDR Ladder Diagram Editor is a graphical tool that enables you to enter and manage Ladder Diagrams. The editor enables quick input using the keyboard. Programming in Ladder Diagram is best suited to applications where mostly binary variables are required and the interlocking and sequencing of digital IO points is the primary control requirement.

User Interface

Content not available yet. 

The Toolbar

The Toolbar

The Menu Bar

The Menu Bar

Context Sensitive Menu

Context sensitive menu

The Status Bar

The Status Bar




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