[51] Why does the solenoid valve burn out repeatedly after being connected to the PLC?
A: When a solenoid valve is connected to an inductive load, it will generate a self-induced electromotive force when it is turned off. This electromotive force will accumulate on the contacts. If the voltage across the contacts is too high, it will break down. If it is a DC solenoid valve, a freewheeling diode can be added. If it is an AC solenoid valve, a surge protector can be added.
[52] Are the storage boxes for FX2N and FX2NC the same?
A: No, they are different. FX2NC-EEPROM-16 is FX2NC, while FX-EEPROM-16 is FX2N.
[53] How to use the built-in analog knob of the PLC (FX1S/FX1N/FX3G)?
A: Values from 0 to 255 are set in the special data register relative to the scale position. This value is designated as the timer's setpoint, allowing it to be configured as a rotary analog timer. VR1 →D8030 (integers 0-255 ) VR2→D8031 (integers 0-255)
[54] How to use a soft element (auxiliary relay state) that retains power during a power outage as a general practice?
A: When using PLCRUN, clear the necessary areas using the ZRST command via the initialization pulse. If you need to clear the power outage holding areas, please use M8032.
【55】 Does the memory cartridge require batteries ?
A: Memory modules other than RAM do not require batteries . However, batteries are needed when using clock functions, auxiliary relays, data registers, and other holding devices . Additionally, batteries are required when using special data registers and special auxiliary relays . Please refer to the programming manual for details .
【56】When the PLC is running , the power LED goes out or flashes?
A: Check if disconnecting the wiring at the (power supply) terminal restores normal operation . If it does , the problem may have been caused by a short circuit in the load or excessive load current, which overloaded the power supply and triggered the protection function . If it does not restore normal operation , please contact Mitsubishi Electric's after-sales service department .
[57] The register corresponding to the analog potentiometer that comes with the FX1S is...
A: The FX1S programmable controller has two built-in potentiometers: VR1: D8030, VR2: D8031.
[58] How to distinguish between genuine Mitsubishi PLCs and high-quality replicas?
A: The market for small PLC products in my country is currently very large, with Mitsubishi series PLCs being the most widely used. However, in recent years, many customers have reported encountering counterfeit or refurbished Mitsubishi products on the market. This analysis will focus on some similar Mitsubishi PLCs and expansion modules currently available to improve customers' ability to distinguish between genuine, counterfeit, and refurbished products.
Currently, the most commonly used Mitsubishi PLCs and expansion modules in the Chinese market are the Mitsubishi FX1S series and Mitsubishi FX2N series PLCs and their corresponding modules. Below, we will analyze various products based on these two series. With the improvement of counterfeiting techniques, it is difficult to distinguish genuine from fake, new from old, Mitsubishi PLCs and expansion modules solely by their appearance. Therefore, the main way to differentiate between genuine and counterfeit, and new and old, Mitsubishi PLCs and expansion modules is to examine their internal circuit boards.
Mitsubishi PLCs and expansion modules can be categorized into two types based on the method of imitation: reverse engineering and independent design. Let's first analyze the reverse engineering type. These products are characterized by identical appearance and completely identical PCB layout and wiring. Most chips are salvaged parts, especially the main CPU, which is almost always a salvaged component. At first glance, it's difficult to spot the flaws, but a closer look at the silkscreen printing on the main chip reveals the deception. The silkscreen printing is usually polished. These products are typically made by salvaging the main CPUs of damaged or old Mitsubishi PLCs. Because the amount of salvaged components is limited, the silkscreen printing and batch numbers of these PLCs are inconsistent. Therefore, to create a uniform model number, counterfeiters simply polish away the original silkscreen printing and print a new model number from the same batch. This makes the polishing of the circuit board immediately obvious. Of course, some polishing techniques are so sophisticated that non-professionals generally cannot detect it. In such cases, checking the version number of the Mitsubishi PLC and expansion module using background software will immediately expose the counterfeit. Anything with the model number 26210, 26212, etc., that isn't 26214 or 26215 is definitely a salvaged part or a refurbished product. Mitsubishi's current version is 26215, and most new machines on the market are 26214 or 26215, so anything not from these two versions is generally a defective product.
Independent Design Type: This can be further divided into partially independent design type and completely independent design type. Partially independent design type means that part of the design is independent, and part is copied. Because mainland China currently lacks the capability to design Mitsubishi CPUs, the CPU boards are copied, while the I/O boards and power supply boards are independently designed. The method for identifying this type of high-quality replica is the same as for the copied type. Completely Independent Design Type: This type of high-quality replica is rare in mainland China and generally comes from Taiwan. It has the highest technological content, with everything newly developed from top to bottom, and it uses the Mitsubishi FX2N series PLC solution. Moreover, the solution may even directly use Mitsubishi's latest 3G solution. Judging from the overall appearance and internal craftsmanship, this type of product should have a certain level of technical sophistication. Even more shocking is that this type of replica also uses Panasonic relays, the same model used in the original Mitsubishi PLC.
[59] Are Mitsubishi PLC simulation software and programming software the same ?
A: The programming software is called GXDeveloper, and the simulation software is called GXSimulator. These are two separate software programs. To perform simulation, you must first install the programming software, and then install the simulation software. The simulation software is essentially a plugin for the programming software, adding simulation functionality. GXSimulator is a plugin that adds simulation functionality to the GXDeveloper software package. It's Mitsubishi's ladder diagram program simulation software used for its Q-series, A-series, and FX-series programmable logic controllers (PLCs). It allows sequential control programs written in GXDeveloper to be simulated and run on a personal computer without needing to be written into the PLC itself. Furthermore, if the intelligent module software package GXConfigurator is also included, simulations of initial parameter settings and automatic parameter refresh for intelligent functional modules (A/D conversion modules, D/A conversion modules, communication conversion modules) can be performed. Using GXSimulator, PLC-related engineers can break free from the constraints of PLC hardware limitations, flexibly and independently performing design and debugging work, significantly improving work efficiency. GXSimulator needs to be used in conjunction with GXDeveloper ladder logic programming software. GXSimulator runs on the Windows operating system. During software installation, you need to first set up the system environment, then install GXDeveloper, and then install GXSimulator. To use it, run the GXDeveloper software, and under the "Tools" submenu in the menu bar, run the "Ladder Logic Test Start" command to simulate and debug the ladder logic program.
[60] When writing programs in GXdeveloper, sometimes after making changes, the corresponding program is not canceled, but an extra step is added. Why does the cursor turn purple in this situation?
A: You can switch between insert mode and overwrite mode using the Insert key. The cursor is purple in insert mode and blue in overwrite mode.
【61】GXdeveloper software cannot compile programs?
A: Click Tools => Options => Runtime Write Settings (After transformation, do not write to PLC; after transformation, set to write to PC, and PC will be written every time a transformation occurs).
[62] When performing floating-point calculations, when converting binary floating-point numbers to decimal floating-point numbers, the value seen in monitoring mode has an error compared to the theoretical value calculated.
A: FXPLC CPU floating-point arithmetic is single-precision, which has a slight deviation. The results will vary slightly depending on the CPU used.
【63】Does the FXPLC have a clock function?
A: The FX1S, FX1N, FX1NC, FX2N, FX3U, FX3UC, and FX3G have a built-in clock function; the FX2NC can be equipped with an option card that includes a clock function.
[64] Will the program be lost after the PLC is powered off?
A: The programs for FX1S, FX1N, FX1NC, and FX3G are stored in EEPROM and will not be lost after power failure; the programs for FX2N, FX2NC, FX3U, and FX3UC are powered by the battery. If a low battery alarm is triggered when the battery is replaced , the program will be lost ; otherwise, there is no low battery alarm and the program will not be lost.
[65] Will the program be lost when the PLC battery is replaced?
A: If a new battery is inserted into the socket within 20 seconds of being unplugged, the program will not be lost. However, if the battery LED is left unused for an extended period after being switched on, the battery voltage may be lower than the specified value. In this case, the program will be lost when the PLC power is cut off.
【66】Does the FXPLC support floating-point operations?
A: FX1S, FX1N, and FX1NC do not support floating-point arithmetic; FX2N, FX2NC, FX3U, FX3UC, and FX3G support floating-point arithmetic, but FX2N, FX2NC, and FX3G only support some of the floating-point instructions supported by FX3U.
【67】How many axes of pulse output does the FXPLC have built-in?
A: All basic units must be transistor output type. FX1S, FX1N, FX1NC, FX2N, and FX2NC have built-in independent 2-axis pulse outputs, but FX2N and FX2NC do not support positioning instructions except for the [D]ABS instruction corresponding to V3.0 and above ; FX3U and FX3UC have built-in independent 3-axis pulse outputs; FX3G: 40/60-point I/O type has built-in independent 3-axis pulse output, and 14/24-point I/O type has built-in independent 2-axis pulse output.
[68] How do I copy comments from one project to another using GXDeveloper?
A: Click "Project" → "Copy" in the menu bar, then click Browse to find the project. You can then choose to copy the program, component comments, parameters, or component memory. Alternatively, you can directly copy the COMMENT.wcd file from "Resource" → "Others" in the program folder to the corresponding folder . You can also use the merge method to copy.
【69】How do I confirm the version of an FX series PLC?
A: You can identify the programmable controller (PLC) version by monitoring the special data register D8001 (decimal number). The first two digits represent the PLC model, and the last three digits represent the version information. For example, if the value of D8001 is 24251, 24 represents the PLC model as FX2N , FX3U , FX3NC , or FX3UC series, and 251 represents the version information as Ver2.51 .
[70] Analysis of the causes of PLC interference suppression measures. Several FX2N PLCs frequently experience input point flickering, causing system malfunctions. It was suggested that adding a 104 capacitor between the input point and the COM port would solve the problem. Indeed, this worked. What is the reason for this, and why is a 104 capacitor specifically required? What is the theoretical basis for this?
A: The theoretical basis is very simple: noise reduction filtering. The reason 104 is used is because the frequency of your ambient noise can be attenuated by 104. And let me tell you, this is the noise reduction rate parameter used in most situations (I'm referring to switching signals). I think calling it a "jack-of-all-trades" is more accurate, because using it won't cause any problems. If it's a frequency signal, it might not be 104; it could be 103 or 102.
[71] What is the extended register (R) in the FX3U, FX3UC, and FX3G series programmable controllers?
A: The extended register (R) is a soft element that extends the data register (D). In the case of FX3U and FX3UC programmable controllers, power-off retention is achieved via battery. In the FX3G programmable controller, power-off retention is generally achieved via a soft element when using battery.
[72] Can the FX series programmable controller maintain the output state during RUN when it is in STOP mode?
A: When the FX series programmable controller drives the special auxiliary relay M8033, the output state during the RUN phase can be maintained after the programmable controller changes from RUN to STOP.
【73】What are index registers (V, Z)?
A: A three-index register is a special register that, in addition to being used in the same way as a data register, can also be used in conjunction with other device numbers and values in application instructions, thereby changing the device number and value in the program. Among the registers, there are two types called index (modifier) registers: V and Z. V and Z are attached to other devices as shown below: [When V0, Z0=5] D100 V0=D105, C20 Z0=C25 ← Device number V□ or Z□ value. Data registers and index registers can be used to indirectly specify the set values of timers and counters, and are also used in application instructions.
[74] What are the consequences when the battery voltage of the FX3U and FX3UC series programmable controllers drops?
A: When the battery voltage drops due to factors such as battery life, it cannot properly maintain the program (when the memory cartridge is not used) and the state of soft components and clock during power outages.
[75] Can the FX3U and FX3UC series programmable controllers use power failure holding soft devices as non-power failure holding soft devices?
A: For FX3U and FX3UC series programmable controllers, depending on the parameter settings, some power-failure holding soft elements can be changed to non-power-failure holding soft elements. However, soft elements specifically designed for power-failure holding cannot be changed to non-power-failure holding soft elements. In this case, the holding soft element is cleared using the initialization pulse (M8002) in the program, allowing it to be used as a non-power-failure holding soft element.
[76] What is the function of the battery in the FX3G series programmable controller?
A: The battery is used when the following content needs to be retained after power loss (battery backup). Additionally, parameters need to be set to retain the current time in the soft component memory. The content backed up via battery includes: auxiliary relays M1536～M7679, status codes S1000～S4095, data registers D1100～D7999, and extended registers R0～R23999. The current time is also retained (backed up by the large capacitor built into the programmable controller at the factory).
[77] What is the maximum number of write cycles allowed for the memory of the FX3U, FX3UC, and FX3G series programmable controllers?
A: The memory cartridge allows for fewer than 10,000 write cycles, and the FX3G programmable controller's built-in memory (EEPROM) allows for fewer than 20,000 write cycles.
【78】What are the effective number of bits and processing range of a binary floating-point number?
A: Significant digits: The significant digits of a binary floating-point number, if represented in decimal, are approximately 7 digits. The range of binary floating-point numbers is as follows: - Minimum absolute value: 1175494 × 10⁻⁴⁴ - Maximum absolute value: 3402823 × 10³²
【79】What is the range specified for a decimal constant?
A: [K] is the symbol for a decimal integer, mainly used to specify the set value of timers and counters, or the value in the operand of application instructions. (For example : K1234) The specified range of decimal constants is as follows: - When using word data (16 bits): K-32768～K32767 - When using 2 words of data (32 bits): K-2 , 147 , 483 , 648～K2 , 147 , 483 , 647
【80】Can FX3U(C) and FX3G directly specify real numbers?
A: In the FX3U, FX3UC, and FX3G series programmable controllers, [E] is a symbol representing a real number (floating-point data), mainly used to specify the value of the operand of the application instruction. (For example : E1.234 or E1.2343 ) The specified range of real numbers is -1.0 ×2¹²⁸ to -1.0 ×2⁻¹²⁶ , 0, 1.0×2⁻¹²⁶ to 1.0 ×2¹²⁸. In sequential control programs, real numbers can be specified in two ways: "normal representation" and "exponential representation". - Normal representation specifies the set value. For example, 10.2345 is specified as E10.2345 . - Exponential representation specifies the set value as (value) × 10ⁿ. For example, 1234 is specified as E1.2343 . [3] in [ E1.2343 ] represents 10 to the power of n (3 is 10³).
[81] Can the bits of a word soft element be directly specified and used as bit data?
A: The bits of the specified word soft element in the FX3U and FX3UC series programmable controllers can be used as bit data. When specifying bits of a word soft element, please use the word soft element number and bit number (hexadecimal) for setting. (For example : D0.0 represents bit number 0 of data register D0.) Indexing cannot be performed on the soft element number or bit number. Target word soft element : Data register or special data register. Bit number : 0～F (hexadecimal) . For example: LDD0.FOUTD0.3
[82] Can the buffer registers of the FX3U and FX3UC series programmable controllers be directly specified?
A: The FX3U and FX3UC series programmable controllers allow direct specification of the BFM (Buffer Memory) for Special Function Blocks (SFCs) and Special Function Units (SFCs). The BFM is a 16-bit or 32-bit word data, primarily used for application instruction operands. The BFM is specified following the module number (U) and BFM number (G) of the SFC. (For example : U0G0 represents BFM#0 for SFC with module number 0.) Furthermore, indexing can be performed within the BFM number. The specified range is as follows: Unit Number (U) 0 ～7 BFM Number (G) 0 ～32766 Example of MOV instruction : MOVK10U0G10 Example of modifying the BFM number : MOVK20U0G10Z0
[83] Can the soft elements used by the LD and LDI instructions be modified using index registers (V, Z)?
A: For FX3U and FX3UC series programmable controllers, the soft elements used in LD and LDI instructions can be modified using index registers (V, Z). (Status (S), special auxiliary relays (M), 32-bit counters (C), and D □ cannot be modified.)
[84] In the soft device used by the LD and LDI instructions, can the bit of the data register (D) be specified?
A: For FX3U and FX3UC series programmable controllers, the bits of the data register (D) can be directly specified in the soft devices used for LD and LDI instructions. When specifying the data register bit by bit, enter " . " after the data register (D) number, followed by the bit number (0~F). Only 16 bits of the data register are valid. Please specify the bit numbers starting from the least significant bit in the order 0 , 1 , 2 , …9 , A , B , …F. For example: LDD0 . 3OUTY0D0. The third bit determines whether the LD contact is ON (conducting) or OFF (not conducting).
[85] Problem with connecting NPN and PNP inputs to Mitsubishi FX series PLCs. Mitsubishi FX series PLCs have an active-low input, meaning NPN photoelectric switches can be used. However, with a PNP photoelectric switch (three-wire system), the signal (black wire) can be connected in series with a 470-ohm resistor, and the logic can be reversed in the program, and it still works. I don't understand why this works.
A: PNP transistors require an external power supply. The FX series are all sinking types, so an external NPN power supply works correctly. PNP transistors are source-type outputs, so they won't work if directly connected.
[86] How to implement automatic cycling with a Mitsubishi PLC? Specifically, I wrote a program that picks up items from one side, places them on a conveyor belt, and stops the conveyor at a certain point. The pusher motor then starts, pushing the items back into the basket below. The problem is that I have to press a switch to give it a pick-up command each time for it to pick up items automatically. Changing the switch to normally closed doesn't work. What instruction can I use to make it pick up items automatically, i.e., to cycle through the system?
A: The command to trigger the switch first activates M0.0 , and then M0.0 activates the steps to grab the object. To achieve the automatic loop function, after the object retracts, triggering M0.0 again is equivalent to manually pressing the switch again, which will then allow you to grab the object again.
【87】What does [DDIVD136D140D128] mean in a Mitsubishi PLC program?
A: DDIV (32-bit division instruction) . D137 , D136 (place dividend) . D141 , D140 (place divisor) . D129 , D128 (place quotient).
[88] How to add comments when writing ladder diagrams in Mitsubishi PLC programming software, GX-Developer 8.52 ?
A: Go to Menu Edit -> Document Generation, select the annotation type, and then double-click the location in the ladder diagram where you want to add the annotation.
[89] What do rising edge contact and falling edge contact mean in Mitsubishi PLC programming software?
A: In Mitsubishi PLC programming software, the rising edge contact and falling edge contact instructions are as follows: PLS (Rising Edge Differential Pulse Output) is a rising edge differential pulse output instruction. It differentiates the rising edge of the specified signal and outputs a pulse signal with a pulse width of one scan cycle. PLF (Falling Edge Differential Pulse Output) is a falling edge differential pulse output instruction. It differentiates the falling edge of the specified signal and outputs a pulse signal with a pulse width of one scan cycle. PLS and PLF are only effective when the input signal changes.
【90】What does Mitsubishi PLC[=D0K0] mean? What does MOVK0DO mean?
A: LDM8000[=D0K0]OUTY0 means that when M8000 is connected and D0 data is equal to 0, Y0 is engaged.
LDM8000[＞D0K0]OUTY0 means that when M8000 is connected, Y0 is engaged when the data in D0 is greater than 0.
LDM8000MOVK0D0 means that M8000 is turned on and transmits data 0 to DO.
【91】What does it mean when the highest bit of a Mitsubishi PLC register is the sign bit?
A: The sign bit in the register is used to indicate whether the data stored in the memory is positive or negative. If the sign bit is 1, the value is negative, and if it is 0, the value is positive.
[92] How to input the ADD command in the Mitsubishi PLC CTX programming software? The command ADDD5V0D20Z0 is not recognized in the programming software . The input method is to press F8 and then input ADDD5V0D20Z0 , but that doesn't work. I searched online and tried inputting D5V0D20Z0, but that still doesn't work.
A: The ADD instruction takes three operands. You need to input ADD as S1S2D*, for example, ADDD40D201ZD40. This instruction means: the value of D40, the value of D(201Z), is stored back in D40. If the value of the Z register is 10, then D(201Z) is D211. Therefore, you should input ADDD5V0D20Z0D, where * represents the register number.
【93】What does T10D8030 mean in Mitsubishi PLC?
A: This means the timing of the T10 is adjusted by the built-in potentiometer VR1D8030 (an integer from 0 to 255), so the maximum is 25.5 seconds.
[94] The program has comments when viewed online, but the comments are gone when I back it up and view it on other computers . Why is that?
A: The comments are saved along with the original program. Mitsubishi PLC comments cannot be saved into the program. They can only be seen when the original program with comments is displayed.
[95] Which is better, Mitsubishi or Delta PLCs ?
A: Mitsubishi PLCs definitely outperform Delta. Mitsubishi is a Japanese-made small-series PLC, known for its stable performance, but it's more expensive than Delta. Delta, on the other hand, is a Taiwanese-made PLC, less established, and its performance stability isn't as good as Mitsubishi, but it's cheaper. So it depends on your application. If the environment is relatively clean, the conditions are not complex, and you want to save money, then you can choose a Delta PLC.
[96] How to put the ladder diagram from Mitsubishi PLC programming software into Word?
A: You can use a printer to print the program. Install a PDF printer, and you can print the program into a document, then insert those documents into a Word document.
[97] How to control the forward and reverse rotation of a DC motor in a Mitsubishi PLC program?
A: Use a digital-to-analog converter (DAC) to output a 0-5V signal. Then, find an external dedicated DC speed controller. The input signal is 0-5V, and the output provides positive feedback based on the different output voltages, corresponding to the voltage levels from lowest to highest. The minimum is 0V, and the maximum is your motor's normal operating voltage. For detailed parameters, please refer to the specifications of the DC speed controller.
【98】Shortcut keys for Mitsubishi PLC programming software. Mitsubishi's programming software has F1~F10 , as well as sF5, sF9, etc. How do I press these keys?
A: Open the Mitsubishi software, open the display menu, click toolbar, and then in the toolbar options, click the solid dot before "Ladder Diagram Symbols" and confirm. This will bring up the "Ladder Diagram Symbols" toolbar. Place it on the side of the window. All the shortcut keys are there. Just use them accordingly. For example, pressing F1 will display a normally open point under the cursor. sF5 means pressing the S and F5 keys simultaneously, which will display the corresponding normally open point connected in parallel upwards. The address needs to be entered separately.
【99】What does INCP mean in Mitsubishi PLC?
A: INCP simply increments the register by 1, with a condition added beforehand . For example, INCPD100 , even if the data inside D100 is continuously 1, it only counts as one increment.
[100] How to set up a Mitsubishi PLC C500 or higher that has power-off retention to a non-power-off retention type?
A: 1. Click the display menu and select Project Data List. 2. Click Parameters on the left and select PLC Parameters. 3. In the FX Parameter Settings dialog box, select Soft Components. 4. Change the latch start value in the Auxiliary Relay item.
