LDMICRO TUTORIAL

 

MedTronic LDMICRO TUTORIAL

 

 

LDMICRO / PIC, AVR, 8051 and ARDUNIO

Programming with LADDER Diagram 

 

Author: Eng.Medhat Saber Ahmed (MedTronic)

 

Ladder: It is a graphical programming language, in the form of a diagram,

Which, because it is easy to create and interpret and represents physical connections between

Electronic components (sensors and actuators), ends up being widely used

In an industrial environment.

In a simple LADDER diagram, we can find three types of

Basic elements:

1) CONTACT:

It is the element that represents the sensor, i.e. the signal input in the logic control block. can Be one switch, a reflective sensor, a limit switch Or even the contact of an auxiliary relay.

S1, S2

 

 

2) COIL (coil): It is the actuating element, that is, the element activated or turned off by the control block

Logical control. It could be a contactor, a

Motor, a lamp, a hearing actuator, etc...

 

 

 

3) MEMORY: or Internal Relay: This is the

Representation of the state of a contact or

Coil in memory, without direct connection to

External elements.

 

There are also other auxiliary elements that allow you to carry out more complex operations.

Complex tasks, such as timing, counting and data manipulation.

 

These elements will be discussed in the second part of this tutorial.

 

See an example of a LADDER diagram:

For this diagram, we have control

Of  3 elements, these being M1, MOT and

CIL1. These elements can be

COILS (ACTUATORS) or

MEMORIES (internal relays).

Elements S1, S2, BE, VC and S3 only

Appear on the left side of the diagram,

In square bracket format [ ], which

Assumes that they are sensors

(Appetizer).

In the first line, we observe that the

Program rule defines that output M1 will activate only if the sensors

S1 and S2 are BOTH turned on.

In the second line of this program, it is observed that the rule determines that the MOT output will turn on if BE is OFF 

(Bar means inversion) and if M1 or MOT is activated 

(At least one of these).

In the third line, it is observed that the CIL1 actuator will activate if the FC sensor

Is OFF (again look at the bar), and if sensor S3 is

Activated.

There are also some other important rules about programming

LADDER:

1) It is not permitted (or at least recommended) to use the same

Coil (output) on more than one line, as the rules will conflict. Per

Example, we could not insert in the previously represented diagram

Another line that would activate the CIL1 actuator.

2) There is the possibility, in some variations of the language, of using

SET and RESET command (on and off) that determines when

a given actuator will turn on or off.

3) There are special blocks that allow you to time, detect pulse, edge,

Counting and other features. This may vary depending on the language

Used.

LADDER FOR PIC MICROCONTROLLER: THE LDMICRO

The LADDER language was born out of the need to facilitate programming

In industrial environments, referring to a high-level and easy-to-use language

Be used. However, there is a program, (LDMICRO) by Jonathan Westhues,

Which allows LADDER programming of microcontrollers, which enables

Study and implementation of very low-cost controls.

This software is very versatile, it does not require installation (just run the

Ldmicro.exe file in a Windows environment or compatible emulator), and is free

Distribution, as we can see in the window below, extracted from the HELP of the

Program in question:

 

LADDER FOR PIC MICROCONTROLLER – THE LDMICRO

The LADDER language was born out of the need to facilitate programming

in industrial environments, referring to a high-level and easy-to-use language

be used. However, there is a program, (LDMICRO) by Jonathan Westhues,

Which allows LADDER programming of microcontrollers, which enables

Study and implementation of very low-cost controls.

This software is very versatile, it does not require installation (just run the

ldmicro.exe file in a Windows environment or compatible emulator), and is free

Distribution, as we can see in the window below, extracted from the HELP of the

Program in question: 

LDMICRO works as follows:

1) Start the executable program (LDMICRO.EXE). The following screen will be displayed: 
 

 

 

It is in this environment that you can generate the LADDER program to

Microcontroller.

To insert a coil, press L.

You will notice that the edited line will be built (or complemented) with the

Indicated coil. It is allowed to insert more than one bobbin for the same line.

 

By double-clicking on the created coil, the dialog box will open. 
 

Coil property: 

If the coil is defined (in the Source field)

As INTERNAL RELAY, the name of the coil

In the ladder diagram will be preceded by the

Letter R. Example: If the coil name is new

(As in the example above), and if this is

Set to Internal Relay, will be displayed

As Renew.

If the coil is set to PIN ON

MCU, the coil name will be preceded by the

Letter Y (in the case of the example, Ynew). 

Please note that when entering a contact or

Coil, the position of the cursor will be respected

(Flashing bar) to define the location of the

Insertion. That is, to insert a coil or

Contact below another, first position the cursor in a horizontal position.

To enter a contact:

Position the cursor at the desired location, and press C.

To enter a contact:

Position the cursor at the desired location, and press C.

Note that a field defined by square brackets --] [--- will appear with the name

Xnew. Double click on this item to open the properties box.

Contact.

In the source field, you can define whether the contact is an internal relay

(Memory). In this case, note that the contact name will be preceded by the

Letter R. If set to INPUT PIN (default), the contact is a sensor, a

Digital signal input. In this case, the contact name will be preceded by the

Letter X (as in the example above: Xnew).

If you want to use a coil as a contact (this is possible in ladder),

Just activate the OUTPUT PIN option. In this case the name of the inserted element

Will be preceded by the letter Y.

The [/] box defines that the input will be negated (with inverted logic),

That is, it activates by zeroing the contact, and deactivates by turning on the contact.

Practice:

Now try to assemble the following LADDER diagram using the resources

Mentioned above:

After editing this program (note that the elements used are

Only and exactly XBOTLIGA, XBOTDESL, YMOTOR). There must not be

No other elements in the program.

SAVING

After writing your program, save it by clicking FILE -> SAVE AS...

Save as a file with the LD extension.

SIMULATING

With the program saved, to simulate the program, click SIMULATE

SIMULATION MODE, and later on SIMULATE

START REAL TIME

SIMULATION.

From this moment on, observe in the panel at the bottom of the window the

State of contacts and coils. Just DOUBLE CLICK on the item

To change your state.

Test by changing the state of the sensors, and see if the program works.

COMPILING.

To generate a HEX file from this program, simply follow these

Steps:

1) Click on SETTINGS

MICROCONTROLER and define which

Microcontroller to be used. For better operation, click

SETTINGS

MCU PARAMETERS and set the clock crystal value

Used. The default is 4MHz.

2) Now double-click on each

DIGITAL IN or DIGITAL OUT element of the

Bottom of the window, associating each

CONTACT or COIL to a pin of the

Microcontroller.

3) Now click on COMPILE

COMPILE

AS.. And indicate the name of the file to be

 
 
Generated. IMPORTANT: Don't forget to

Place the HEX extension. Ex: PROG.HEX.

If you do not enter the extension, it will be

Harder to find it later with the program

Recording (EPIC, ICPROG, etc...)

Most used commands:

Insert new line shift V or shift 6

Insert a semicolon comment

Detects rising edge/

Detect falling edge\

Timer to turn off F

Timer to turn on

Timer to turn on T retentive

Incremental counter U

Decremental counter I

Circular counter J

Compare equality =

Compare whether it is bigger >

Compare whether it is smaller <

Compare whether it is greater or equal.

Compare whether it is less or equal,

Insert L COIL

Insert Contact C

Insert E counter reset

Load variable with value M

Insert sum + operation

Insert subtraction operation -

Inserts multiplication operation. *

Inserts division operation D

Analog P reading

Exercises:

Try running the following LADDER programs on the microcontroller:

Exercises:

Try running the following LADDER programs on the microcontroller:

1)

Note: To insert a line, use SHIFT + V

Note the CORRECT names of the items involved:

XB1: Button 1 of the two-manual system.

XB2: Button 2 of the bi-manual system.

XEMERGENCY: Emergency button. If OK, it is at 1. Pressed at 0.

YMORSA: VISE actuator, which holds the part. Call with a bot. press.

YPRENSA: PRESS actuator, only turns on when pressed. the 2 buttons.

YBUZZER : Audible alert. It must indicate emergency triggered (at zero).

RPISHING: Auxiliary relay that will flash every 400 ms.

2) Try adding a part sensor to the above system. If the part does not

    Is detected, the walrus should not start.

3) Now also add a beep indicating whether a button has been

    Pressed and the part was not placed.

2) Try creating the ladder scheme for a garage door. Use the

Following elements:

XBOTAO: Remote control button.

XOPEN: End of travel sensor that determines that the gate is

Open

XCLOSED: End-of-stroke sensor that determines that the gate is

Closed

XIMPACTO: Impact sensor. Detects that the gate has collided with something.

YMOT_OPEN: Motor that moves the gate towards opening.

YMOT_FECHA: Motor that moves the gate towards closing.

Use your creativity. Simulate the program in the ladder environment, and on the station

w/ PIC microcontroller. Good job.

PART 2: DESCRIPTION OF LDmicro COMMANDS

1. Comment insertion

2. Contact insertion

3. Rising edge (pulse) detection

4. Falling edge (pulse) detection

5. Power-on timer

6. Shutdown timer

7. Retentive power-on timing

8. Increment counter

9. Decrement counter

10. Circular counter

11. Comparison – equal

12. Comparison – different

13. Comparison – bigger

14. Comparison – greater or equal

15. Comparison – smaller

16. Comparison – less than or equal

17. Open circuit

18. Closed circuit

19. Main (general) control relay

20. Insert coil

21. Enter counter/timer reset

22. Data movement (attribution)

23. Addition (16 bits)

24. Subtraction (16 bits)

25. Multiplication (16 bits)

26. Division (16 bits)

27. Shift Register

28. Table (look-up)

29. Table of values ​​(linear association)

30. String formatted by serial

31. Insert serial output

32. Insert input via serial

33. Activate PWM

34. Insert A/D reading

35. Sets value as persistent in EEPROM

Translation of LDmicro's HELP, document by Jonathan Westhues, carried out by    

 MedTronic, in December 2023