Ledger diagram of PLC.

By IKTech May 29, 2017

Let’s talk about your Ledger diagram today. There is a need for several contacts, coils, timers, quarters, etc. to diagram the ladder. At first we will write the details of the words. Then the name and description of the device will be given. At the end, combining the code with the program was created.

Note the following:

1. Normal Open Contact

2. Normal Close Contact

3. Vertex line

4. Horizontal line

5. Normal Open Coil

6. Normal Close Coil

7. PLC Inventory Cable etc.


It is possible to work with just a few of these. Hopefully from the above pictures, I know Open, close contact, coil and the architecture. This image is programmed with Aman’s software.

Figure C0001, C0003 and C0004 are open contacts, C0002 is close contact, 0.01 is open coil, 0.02 close quote. Vertical and horizontal lines are shown with red arrows. Many uses of the architecture, timers, counters, different types of data transfer, special relays, and many other uses. See the picture has been done to complete counters and programmers with the same anointing. It has changed the character through the name of the device.
Device name and description

This is one thing that the device is named after the PLC CPU. Now a question arises as to whether the name of a device based on a CPU can be named. The correct solution is to use the name and use of the device, based on the CPU based on its use rules book. If you search Google, hope you find all the books.

I will discuss with you about P. L. Sear device of Mitsubishi FX series. Notice the name of the device and the name of the Mitsubishi device is not the same. With immersion “C” and with Mitsubishi “X”
Description of FX Series device

X-Physical Input:

X addresses are used to name a physical input.

Y-Physical Output

Y devices are used to name a physical output.

M-auxiliary relay

M-Relays Internal Bit Device It is possible to use internal bits if any functions are needed. When an M device coil is active, the M Device contacts become active.

There is a function group dedicated to M Device. They M8000 ~ M8511 The description of each of these functions will be found in the programming language of FX.

S-State Relay

S relay internal bit device. They are used in the STL (Initial State) programming, or the steps in the ladder logic code indicate the activation signal. If STL programming is not used, Mbit can be used as a bit in this manner.

It is used as a fault propagator. S900 ~ S999 can be used as a fault indicator. Whose data is available in the FX manual.


Ti device is a timer device with a default timer 100msec overtime, 10msec increments, or 1msec extra time depending on the timer address. Most timers depend on their address. And some of them are non-retentive. That is, they do not hold the current time, the input condition is good. Retourive at the top of T246 They hold their values ​​until they’re reset. Retentive timer is based on 100msec or 1msec time depending on the input address.

When the preset value associated with a timer is active in the device call, the associated device connection is also active as its identity. All timers are 16 bits, which means the maximum presets are +32767. Valid presets are K value and D data registers. The maximum time for a 100msec timer is 3276.7 seconds. Timer’s value backup is in the backup battery, so if the battery is bad quality or disconnected the timer will be reset.

C- Counter:

C device is counter device. Its ideal is retention, retains the counter number until it is reset. And the retention job is a backup battery. When a counter-associated preset standard is active in C device connection, the corresponding C device contact is also active as its identity. Counter can be 16 or 32 bits, which means the maximum counting range is -32768 to +32767 (16 bits) or -2,147,483,648 to 2,147,483,647 (32 bits). Negative presets are not used too much. Valid presets are K value and D data registers.

Generally there are three types of counter. 16 bit up counter, 32 bit up / down counter and 32 bit high speed counter. High speed counter is again three types, 1 phase, 2 phase and A / B phase counters. More from the Counter’s Details Manual.

Stay here today. The next tune will be …

D – Register Data, R and ER – Register and Extension File to Register, V and Z – Index Register, P – Pointer, K, H, and E – Numerical Constant, U \ G – Buffer Memory Access.

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