Data files not downloading to program

[JDHammond 0]

Every time we load a program into the PLC, everything in our data registers in the PLC, and the HMI go to a default setting. We havent noticed this problem before because we always did online changes. We have settings for servo positions in the PLC and HMI to alot of epuipment. It takes a couple of days to get it back the way we want it. When I save a program, the data registers arent saved? If they are why dont they get downloaded back into the PLC. Am I saving the project wrong or something?

[Gambit 327]

Actually the Register data should will only be cleared if you reset the CPU. If you do not want certain registers to be cleared you can Latch them. They can then only be cleared via a latch clear. You can also use File registers to store your data if you do not want them to be cleared ever. Downloading a project will only download the program code. Since you're american i'm guessing you're using GX Developer. In GX you can create a device memory to which you can save you're device data which you can then sent back to the PLC if needed. Edited 27 May 2008 by Gambit

[JDHammond 0]

We have positions for the servos the hardly ever need changing. So ur saying instead of using Data files, I need to use File registers? These registers wont clear if the PLC is reset? I have 300 or more of these data files that I would have to change. Is there a easier way? I see the device memory on the project list on the right, how do I create a device memory? I appreciate your help!

[Gambit 327]

right mouse click on Device memory New => press OK {You should now have a MAIN File under Device Memory,You can create more than one!!! } Now if you go to "write to PLC" or "Read from PLC". You have the option to read the data files into the device memory file. Latching If the register are sequential you can latch the files in the paramter list under devices.

[JDHammond 0]

Can I create this while running??

[Gambit 327]

Yes just create the File and upload the register information

[Crossbow 296]

I think his problem is the stop and start of the PLC erases the memory which is not set as retentive. Set the start and stop addresses for retention in the PLC parameters on the Device tab. If you stop the PLC, then all values not in retentive memory areas are erased, just as they are when you power off the PLC. And parameter settings cannot be made while the PLC is running. You need to stop it and download the parameters.

[JDHammond 0]

In the device tab I have 12K for data registers, Latch (1) Start has 0 in it and Latch (1) End has 9999. What is this? I have nothing in Latch (2) or Local Start/End. Also doing this will it save these when I upload a change to the program? I really appreciate the help, I was trained on Allen Bradley and I guess I got spoiled because this is already done for you. Also, I have download so many Mitsubishi manuals I dont know to do with them. Did you all get this knowledge from training, reading, or just been there done that???

[Gambit 327]

1) You should look at Device memory files as excel sheets wich can be loaded to or from the PLC. The PLC will use these values as initial values and can be overwritteen by the program, so if the PLC is rst the values will be gone. 2) Latch devices will not loose there values when you stop or rst the PLC. So you have 12000 Registers Registers D0 - D9999 are latched and will not be cleared (then can be cleared by using the latch clear switch in your CPU) D10000 - D12000 are cleared when you reset the PLC. Edited 28 May 2008 by Gambit

[JDHammond 0]

I found in the manual that Latch 1 range can be cleared with the latch clear switch on the CPU, and Latch 2 cannot be cleared. So do I need to put that range in Latch 2?

[Crossbow 296]

You need to put it wherever you want. If you use Latch 2, then they cannot be cleared from the key. If you might want to clear them from the key, use Latch 1. Your call.

[Colin Carpenter 10]

That's the one I always use, because they can't be cleared or altered by anything other than the programming software, HMI or similar. I think they're almost as secure as File Registers (as long as the battery holds up), but stand to be corrected. If you select Latch 1 then a maintenance guy can reset all the stored values to zero with the flick of a key on the CPU .... If you don't set them to either, then every time you download a programme or power down the PLC, they will all reset to zero. Most AB PLCs upload and download the data registers by default, but that can cause problems as well, as re-loading previous software version in the event of problems will re-instate the conditions that were current when the previous software version was uploaded. Personally, I find the Mitsubishi way less hassle, but it would be nice to have the choice with AB. Edited 28 May 2008 by Colin Carpenter

[JDHammond 0]

I think I will go with the Latch 2, because I am the one the switched it, not knowing what it was. I actually didnt see it until later! I know if I made that mistake, some other maintenance guy will! Then there goes 12 hours of production!!!

[JDHammond 0]

Also, how do I when I read from the PLC, get what ever is in the data files saved to the program? So I can have the up to date registers? The when I write to PLC those files get put back in them registers, Instead of intial values, or what was saved under the latch? Is that what the file registers are for??

[Gambit 327]

The program and values in registers are two seperate things. When you upload or download you can choose wether or not to download the program , parameters and initial values. Latching will only back-up the values in the PLC so they aren't cleared at rst. However values in registers can always be changed via the program, the software or writing another device memory file. The only difference between fileregisters and latch registers is that they will keep the're value even if the back-up battery is emty unless you put them on RAM memory Edited 29 May 2008 by Gambit

[Colin Carpenter 10]

As Gambit says, the data registers and programme areas are two separate things in the Mitsubishi world. If you come from an AB background, then the two are linked together. If you upload or download a programme, then the data register values ( the data tables) upload or download along with the programme. You have no option in this, which I think is wrong. I once had to download (to the SLC500) a security back up programme a few hours after we had made it. This meant that the data tables which were made at the time also had to be downloaded and the plant regressed to a state which existed a few hours before. The next 5 or 6 hours were spent having to change values to reflect the state that the plant had moved on to. Nightmare!! With Mitsubishis, whenever you download a programme (or programme and parameters), that is ALL you download. The security of the values in the data registers depends on how you have set them up. Latch 2 - Remain as they are unless changed by HMI, programming software etc. Cannot be reset by the key on the PLC. Latch 1 - As Latch 2, but can be reset by the key on the PLC. No Latch - Not sure if they change on programme download, but will certainly revert to zero in the event of loss of power to the PLC. If you want to upload / download data register values to the PLC, then you use DEVICE EDIT. I use IEC Developer, but the same thing will exist in GX Developer. On the attached graphic you can see the way to to do it. (Right click on the main box to get the smaller box.) So, if you want to upload the values that are in (say) D0 to D100, set up the range, then click on READ FROM PLC. To save these values to your PC, click on WRITE TO FILE. To write these saved values into a new PLC (or one that has lost its values), click on READ FROM FILE, then WRITE TO PLC to send those values to the registers shown. A much better way IMHO.

[JDHammond 0]

Thank you all for all your help!!!

[python01 1]

Is there latch reset on the Q00J PLC as well? I don't see one just by looking at it.

[Crossbow 296]

Basic model CPUs (Q00J to Q01CPU) do not have the latch clear function.