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Thank you for your reply Inntele, We had already bought the Q system and sent the technical data sheets to the customer, so we can't change the PLC. But we ordered a second CPU, power supply and main base unit for the second PLC system. Now we have 2 identical Q PLC's. One output from de PLC1 is connected to the input of the PLC2 and one output of the PLC2 is connected to the input of the PLC1. If the PLC1 is master then all the outputs of the PLC2 are disabled, the modbus master is disabled (using the FB is easy to start/stop communication). Other problems would be: 1. GOT HMI: how configure (write the same value in the same address in PLC1 and PLC2) both PLC's. 2. GOT HMI: how to control the actuators from the right PLC (base screen) 3. PLC: How to enable/disable modbus slave from one PLC or the other. Anyway, the idea is that the system works... and easier than I expected.

Hi Inntele, Thanks a lot for your advices and expertise! Yes, this is the way we were thinking to do: inputs and outputs to be connected in parallel, and modbus modules from the second PLC not active. 1. About the redundancy, these are their condition: - the processor unit number: 2; processors operate redundantly. - switching active processor does not influence the communication path and does not cause switching between communication paths (one channel would be modbus slave). 2. I don't know how GOT 1455 could or should communicate with both CPU's. The setting should be done in both CPU's because when the second PLC takes control it should run with the same settings. Thank you!

Hello, Our customer asks for a PLC with redundant CPU. Because the process is not critical and from financial reasons we decided to came up with a Multi CPU system. We are thinking there are 3 possibilities: 1. Multi CPU system: 2 CPU. Double each I/O module, one module for each CPU. The disadvantage is that when a error occurs in the CPU no. 1, the error occurs in all other CPU modules and the multiple CPU system stops. So this system is not suitable. 2. Multi CPU system: 3 CPU. The same system. The second and the third CPU will be responsible with controlling the process. First CPU will be dummy CPU, no written logic. 3. Two separate CPU systems each with his own base unit. Here there should be some communication between the two CPU's and one digital output from PLC1 to be connected in one digital input of PLC2 and vice versa. The system has: 16 DI, 8 DO, 8 AI, one QJ71MB91 communication module and one QJ71E71-100 Ethernet module. Q03UDE CPU. One GOT 1455 - should communicate with both CPU's. Has someone did this before? Or do you have some recommendation which system is simplest or more reliable? Thank you.

Scripts are not supported on GT 1020.

You can also use this tool to make your configuration: http://tools.mitsubishi-automation.com/fselection/ At System Overview you can see the addresses.

Did somebody successfully converted a GX Works 2 Structured Project to GX Works 3? Looks like only Simple Project's can be converted. GX Works 3 v1.007H

Hello, I am working on a project on a FX5U PLC. First: this is a completely different programming environment. GX Works 2 and GX IEC Developer were similar, but this is way different. Cons: - if you work on FX5U PLC you don't have any support for libraries. You can only create your own FB's. The FB's can be used in another project by Copy/Paste. - I couldn't convert a FX3U project created in GX Works 2 (latest version) in FX5U project, even if the documentation states that this is possible. - some instructions have different syntax (eg: TO and FROM instructions) and you have to be careful when manually converting programs. - there are no Networks to divide the POU (like in GX Works 2 or GX IEC Developer). - no IL, MELSEC IL, SFC languages. Pro: - the new syntax of some instructions (eg: TO and FROM) is more intuitive. - the help documentation. Very easy to find the manual you need and to download it. Very easy to find a newer version of the manual. - the simple Ladder POU's and the structured Ladder/FBD POU's can be mixed in the same project. This was not possible in GX Works 2. These are just the first observations that come in my mind.

Thank you! I've found this version: W342-E1-15.

Hello, I am not familiar with the Omron PLC's. A PC is connected to the peripheral port of an CJ1M CPU12 PLC. The write command the PC is transmitting to the PLC looks like this (ASCII): "@00WD0070010055*." Can you tell me what kind of communication protocol it is using? It is a public or proprietary protocol? Thank you!

Hello, In the latest version of GX Works 2 it is not possible to use IL language any more. Why did they removed this programming language? I have a project that uses a library (from Mitsubishi) partially written in Melsec IL and now I can't open the project. What options do I have? Thank you!

I have received the FX3G-EEPROM-32L memory cassette. After testing it, I can tell that the Read and Write functions (32L <-> PLC) are available only when the memory cassette and the PLC are not password protected. If one of them is password protected or if both are password protected (with the same password!), then the transfer will not occur. I will have to find another solution.

It is working fine. I use 2 FB's but I only one TCP Client. There is no one to connect to the other function.

This is exactly what I intend to do. I will order one to test it. Thank you!

Sorry, FX3G PLC.

Hello, Can a password protected PLC be updated with a help a memory cassette? The documentation states that it is not possible. But if the memory cassette is protected with the same keyword? Thank you.

Hallo, Maybe you didn't write the Option OS/Object Script to the GOT. I had the same problem.

I use GW2 version 1.91V. I have just created a new program with only one task, POU. Because the PLC is not available I used the simulation instead and the problem persists. FC7_Flow_Rate is a single precision float. I have observed that the lower limit of the float (single precision) type is given by the exponent. So the exponent should be greater then 0. The method for situation like this would be: -verify the Exponent (bit30 to bit 23) is greater the zero, if not, make the float zero -verify the float value is between minimum and maximum in such way that the result should be a normalized float that is recognized by the PLC. If the result is not normalized fatal Error occurs and PLC goes in STOP. Other possibility would be to change the mode that the error is managed: Parameter Setting/PLC RAS/ Operating Mode When There is an Error/ Computation Error : Stop->Continue. But I don't know what other consequences would have on the normal functioning.

The PLC reads the value of the flow rate through modbus protocol from another device. This is not the real value of the flow rate because I receive an inverted float (the two int16 registers are inverted). But this error made me think what if an erroneous reading is happening.

The same error occurs. I could verify the mantissa or the exponent but it a little more complicated because I don't know what are the conditions of error.

Hello, I have the following error with the following float value. First I was not using the limiting condition and this error show up when "E/" instruction was executing. But I wanted to eliminate this exception and introduced the limiting condition GT and LT. Still the same error. In the manual specifies that no error can not occur in GT, LT instructions. Do you have any idea how to manage this exception? The error make PLC stop so is pretty serious.

Yes, I want to enable/disable groups of holding registers: If M0=1 -> enable group 1 holding register D0-D100 If M0=0 -> disable group 1 Tried with QJMB91ModbusSerial_V120 Slave, but it is working all the time. I will try the example from the manual "9.2.2 MODBUS® device assignment parameters- Figure 9.18 MODBUS device assignment parameter setting program example". Another question: first channel is programmed as master with automatic communication. If I try to read more than 45 holding registers from the slave the module returns one of the errors: 7411, 7378 and the data is not updated. I have set a larger value (100) for the Response monitoring timer, but the problem still persists. I have tried reading data from PC and it works fine. I believe that the Slave doesn't send the entire packet in a single sequence, and the PLC does not wait the other sequences.

The registers I want to enable/disable the write rights are holding registers. I want that the write acces to be enable/disable depending on the value of bool registry. Thank you.

Yes, only when the conditions in figure 9.24 are met. The other channel should be programmed in slave mode. I have tested the with Modbus Device Assignment Parameter and it works well. But I need a part of registers to have read/write access or only read access depending of the value of a BOOL register. Or at least to have Read/Write permission or no access to that part of the registers. Thank you.

Both communication types can be used: QJ71MB91 User's Manual 080578 - chapter 9.2.3. Tested and working with MBREQ function. Two observations: 1. Function QJMB91ModbusSerialMasterAutoCh1, doesn't work properly in my sistem: the write command is send but the data that was sent was not updated. - write value of D0 to reg1 in slave - change the value of D0 - only after 2-4 cycles the updated value of D0 is sent. 2. The QJMB91ModbusSerialMaster is working fine. But if an on-line change of the program were the function is located, is made, the function stops working! No reset of power off won't do the job. To make it start again, a "Rebuild All" and a write to controller must be executed. Any idea why? I have seen that MBR is used in the function.

Hi everyone! CPU: Q03UDE. GX Works 2 1.91V. The program should read bits and integers from a slave. But when certain bit change state a write command (write single bit or write single integer) should be issued to the slave. The adress of the register to be written in different depending on the bit that is activated. So far I have tried to test the QJMB91ModbusSerial_V120 example. Only Automatic communication mode example is working, the other example using dedicated instruction just doesn't work. The plan is to use Automatic communication mode for sequential reading the Slave and using dedicated instruction for writing a bit or an register when necessary, but I didn't succeed using dedicated instruction so far. Any suggestions? Thank you.