Tag Archives: Mitsubishi PLC

What is the meaning of Mitsubishi PLC constant H?

The Mitsubishi PLC constant H represents a hexadecimal number and is mainly used to indicate the operational value of the application function instruction.

K is a symbol indicating a decimal integer. It is mainly used to specify the set value of the timer or counter and the value in the operand of the application function instruction. H is a hexadecimal number, which is mainly used to indicate the operation value of the application function instruction. For example, 20 is expressed as K20 in decimal and H14 in hexadecimal.

How to use the M command in Mitsubishi plc

Mitsubishi plc M: Auxiliary relay (equivalent to the intermediate relay in the electrical diagram). His control method is the same as Y, but there is no output port, just a single device. Like Y, there are coils and normally open, normally closed contacts.

When multiple control methods use the same type of Y. At this time, direct control may cross, and the program may appear complicated. At this time, you can use M to control.

For example: you have to control 5 different modes of Y0. If you control Y0 directly, it will generate a lot of interlocks (you should prevent the other 4 modes from working when you use one mode) to make the program complicated and error-prone. (At this time, you will feel that if there are 5 Y0, then how good it will be, but if you use it again, there will be double coils.) If you use 1 M coil instead of Y0 coil for each control mode. Then use the contacts of the respective M to control Y0. When M gets electricity. Y0 will also be powered. (Is it equivalent to 5 Y0)

M: FX2N series range (default) M0-M499 is a normal auxiliary relay M500–M1023 is a latch auxiliary relay (power-off retention type)

Mitsubishi plc programming Ladder diagram: motor is rotating for 10 seconds, inversion for 8 seconds, cycle

Ladder diagram:

Press X0, M0 is energized and self-locked.
At the same time, KT1 is turned on and Y0 is output. At this time, the motor is rotating 10S.

When the 10S time is up, T1 disconnects YO, and M1 is powered on and locked.

At the same time Y1 output, the motor is reversed.

KT28 seconds to the time, M0 reset, at this time a working cycle is over, automatically enter the next cycle.

How to use the ALT instruction in Mitsubishi PLC

ALT instruction is alternate output
Assume that Y0 is the indicator light.
At this time, Y0 is off, and when X0 is pressed, the indicator lights up. Press again to turn off the light, then press it again. It’s as simple as that, it will alternate output. This can also be used as a single button to start the stop program!
Just use it when using the rising edge to achieve the alternation. If X0 does not use the rising edge, it is very likely that the PLC has actually read this switch twice.

How to input Mitsubishi PLC programming instruction MC

Mitsubishi PLC master control MC input method:

When writing the MC master command, first press F8 to enter the input command format.

Then write MC space N0, space Mx press the confirm button to complete;

When the master control speed is fast, press F8 to input MCR, and the space Nx is confirmed and completed.
Note: The master command can be used seven times, from N0 to N7.


The main reason is that the program written by PLC has made mistakes, some of which may be logical errors, or may be input errors. You have to check it out.
Programmable logic controller (programmable logic controller), which uses a class of programmable memory used in its internal storage program, executes user oriented instructions such as logic operation, sequence control, timing, counting and arithmetic operation, and controls various types of machinery or production process by digital or analog input / output.

What does K2Y000 mean in MITSUBISHI PLC?

K4Y0 is 2 bytes y0-y17
K2Y0 is 1 bytes y0-y7

For example: [K85 K2Y000] Corresponds to k85 conversion binary 1010101 to the state of y0-y7.

In the Mitsubishi PLC program, it is often seen that K4M100, K7M500, K1X0, K2Y0, etc. are written.

KnM refers to consecutive 4n bits starting with M. For example, K4M100 is a continuous 4*4=16 addresses starting with M100, which means M100 to M115. These 16 bits are just the length of one word. If it is K7M500, it means 7*4=28 bits starting with M500, more than 16 bits, 32 bits of light rain, so double word instructions should be used when appearing in the program.

These are generally used to transfer instructions and compare instructions. The format used is generally as follows:

= K4M100 K0

The 16-bit contact comparison command, the M100-M115 has a total of 16 bits off, and the contact is turned on.

<> K4M100 K50

16-bit contact comparison command. When the value represented by the 16-bit word of M100-M115 is not equal to 50, the contact is turned on.

D= K7M500 K0

The 32-bit contact comparison command, the M500-M527 has a total of 28 bits off, and the contact is turned on.


16-bit transfer instruction, all of Y0-Y3 are reset.


The 16-bit transfer instruction, X0-X3, a total of 8 bits representing the value is transferred to D0.

DMOV K6M50 D50

The 32-bit transfer command, the value represented by 24 bits of the M50-M523 is transferred to the D50.

CMP K1X0 K1Y0 M10

16-bit comparison instruction, the data composed of X0-X3 is compared with the data composed of Y0-Y3, the former is larger than the latter, M10=1, the former = the latter, M11=1, the former is the latter, M12= 1.

DCMP K5X0 K5M0 M100

32-bit comparison instruction, the data composed of X0-X23 is compared with the data composed of M0-M23, the former is larger than the latter, M100=1, the former = the latter, M101=1, the former is the latter, M102= 1.

Setting the S7-300 address register address

L 0
L   3500
RLD   3
L DBW [AR1, P#0.0]   //Read DB100.DBW3500

But after the address >4095, with 4096 values RLD 3 is greater than or equal to the value of 32768
Error value in the AR1 (great value).
So that there are 3 to the left has been unable to obtain the correct address.
Ask you what other solutions are there? Thank you.
Here is my reply: procedures will be further simplified procedures in the figure below:
L#4500 is a two-character constant, so there is no limit of 4095.
The address byte address is 4500 pointer constants P#4500.0, bits within a byte address of 0,P#4500.0 is equivalent to 3500 with 8 product (with bits of the integer). RLD 3 (left 3) equivalent multiplied by 8.

Siemens RCV/XMT order questions and answers

S7-200 communication ports can be set to free port mode of the CPU. Freedom of choice of mode, the operation of the user program can completely control a communications port, communications protocols are completely controlled by the user program.

S7-200 communication port on the CPU in the electrical RS-485 is standard on half-duplex serial communications port. The serial character of communication formats can include

A start bit

7or 8-bit characters (data bytes)

An odd/even parity bit, or there is no parity bit

One stop bit

Free port baud rate communication speed can be set to 1200, 2400, 4800, 9600, 19200, 38400, 57600 or 112500.

All serial communication devices conform to these formats, can in theory and S7-200 CPU communication.

Free mode you can use. Two directives Micro/WIN (USS and Modbus RTU) is to use a free port mode programmatic implementation.

Also need to be aware of are:

Free port communication in the program when debugging, you can use the PC/PPI cable (set to the free port communication mode) connect PC and CPU, serial debug software running on the PC (or Windows HyperTerminal Hyper Terminal-) debugging free program.

USB/PPI cable and the CP card free port debugging is not supported.

Free communications first communications outlet is defined as the free port mode, and set the corresponding communication baud rate and the communication format. User program through a special memory SMB30 (port 0), SMB130 (port 1) controlling communication mode.

CPU communication interface works in free mode, the communication on other communication protocols are not supported (such as PPI), this communication can no longer communicate with the programming software Micro/WIN. When the CPU is stopped, free port does not work, Micro/WIN will be able to communicate with the CPU.

Communication mode, are procedures defined by the user at run time.

If debugging needs to switch between free port and PPI mode, you can use the SM0.7 mode of the State communications and SM0.7 reflects the CPU running the switch position (at RUN time SM0.7= 1 SM0.7= in the STOP 0)

Core instructions are sent free port communication (XMT) and receive (RCV) instruction. In the free port of interrupted receive instruction end interrupt, send orders to end interrupt, as well as the communication port receives an interrupt.

Reading and writing instruction with the network (NetR/NetW) is similar to user programs cannot directly control the communications chips and have to go through the operating system. User programs use communications data buffers and special storage and exchange of information related to operating system.

XMT and RCV instructions similar to the data buffer, start byte for number of characters need to be sent or received, followed by a data byte itself. If a message was received which was included in the starting or ending character, they are data bytes.

XMT and RCV instruction is called simply the specified communication port and the starting byte address of the data buffer.

Also, note that:

XMT and RCV instructions NetW/NetR instructions are different, they communicate with the network address, and the only communication ports for local actions. If you have more than one device on your network, and must contain the address information in the message; the message containing the address information is XMT and RCV instruction processing objects.

Due to S7-200 communication port half duplex RS-485, XMT directive cannot and RCV instruction effectively.

XMT (send) instructions of use is relatively simple. RCV (receive) commands needed to control a little more.

RCV directives the basic process is as follows:

When the logical condition is met, start (a) RCV instructions into receiving a wait state

Monitoring communications port, waiting for messages set the starting condition is satisfied, then enter the message received

If you set the message of the end conditions are met, then an end message, then exit the receiving State

Therefore, RCV does not necessarily have to receive messages after the instruction starts, if not let it start message receiving conditions, has been in a State of waiting to receive if messages without beginning or end, communication has been in the receiving State. If you try to execute XMT instructions, it does not send any messages.

So make sure to both XMT and RCV very important, you can use the send and receive complete interruption of their complete feature, start another command in the interrupt routine.

In the S7-200 system manual on XMT and RCV instruction using an example. This classic, we strongly recommend learning through this example at the free port.

S7-200 CPU character interrupt function provides communications, communications receiving character will generate an interrupt, SMB2 received characters staged special memory. Communications port Port0, Port1 SMB2, but different character of two interruptions.

Each received a character, it will generate an interrupt. For sending messages in a row, you need to arrange individual character in the interrupt service routine to a userdefined message in the save area. To implement this functionality may use indirection better.

For high speed, characters interrupt requires interrupt program execution speed is fast enough.

Under normal circumstances, using the character as the end RCV instructions the end conditions are relatively reliable. If the communication object variable with one of the characters in the message frame (in bytes) end (check code), should provide news or Modbus ASCII as a condition to end RCV instructions. But often a communication object may not have strict agreements, work may not be reliable, and this may cause RCV does not end normally. This case can receive interrupt with character features.

How artificial end RCV receive status?

Command and control bytes received (SMB87/SMB187) en can be used to enable/disable receiving States. En can be set to 0, and then perform the RCV on this port directive, end RCV instructions. (Remember, the control bytes after the assignment, RCV instruction must be executed, otherwise the receiving State does not end)

Need to communicate regularly send a message and wait for a response message, if the message is not received, the next message could not be sent to do?

Can start when a message is sent with the artificial suspension RCV instruction program.

Freedom communications, send data to the master to the slave, why received more from the station‘s chaotic response?

It shows from the station under the main station required to send messages. Has multiple communication networks from the station, from the station must be able to determine your home station message is not to own, that would require a necessary judgment function of the communication program.

Free port communication protocol is what?

By definition, no free port of the standard agreement. Users can set themselves an agreement.

New PC/PPI cable can support the free port?

New RS-232/PPI cable (6ES7 901-3CB30-0XA0) can support the free port but need to set the DIP switch 5 to 0, and set the appropriate speed.

New USB/PPI cable (6ES7 901-3DB30-0XA0) do not support free port.

Has been used to free port communications port, can connect the operator panel (HMI)?

You can use a CPU with two communication ports, or use EM277 HMI extension connector. If other vendors HMI to consult them.


Knowna communications object character (byte) transport format has two stop bits, S7-200 does it support?

Character format is the most basic hardware (chips) decide; S7-200 chip does not support this format.

S7-200 supports the communication baud rate stated on the manual for the S7-200 system other than the special rate?

Communication speed is determined by the basic hardware (chips) decide; S7-200 chip does not support communication rate did not include this in the manual.

Mitsubishi PLC classified

Mitsubishi MELSEC series can be divided into small and large series. Small series for the FX series maximum 256 I/O points, large series I/O points up to 8,192 points, and has a rich network of Q, QnA series and aseries. Among them, the QSeries high performance CPU will not only have access to QSeries modules, and are compatible with the previous a and AnS the various modules and hardware configuration. QSeries CPU can only use the Q Series modules. Composed in PLC system, the Q Series PLC each slot can be installed any digital module, analog module, Web module, communication module.

Mitsubishi Q Series PLC power supply module

Power supply modules installed on a base plate, each module provides 5 v DC power supply. The installed power supply module model depending on the substrate. In the Q Series PLC Q3 or Q6bb, Q61P-A-Q6p power supply module can be used; in the AnS series QAIS6b on an extended base plate, you can use the AIS61PN, AIS62PN, or AIS63PN power supply module

Mitsubishi Q Series PLC inputs (x)

Input is done by button, switch, limit switch, digital switches and other peripherals to the PLC transmits commands and data. Enter a refreshing entry and direct access input. Refresh Refreshes when the input is at the END, read from all input devices together. In a sequential program by xdirect access input refers to each touch point commands directly from the input modules reads the input signal, DX in the sequence control program said.

Mitsubishi Q Series PLC output (Y)

Output refers to the procedure of control results to the outside coil, such as lights, digital display output. Output refresh, and direct access to the output. Flushes the output is at the END when refreshed on total output module output together, in sequence control program using y; direct access to the output means each coil command, output signal directly to the output module, DYin the sequence control program said.