DeviceNet communication between CJ1GCPU45SP and CJ1MCPU13

[python01]

Hello everyone, I need to modify furnace ladder diagram to take control of the upper PID limit. The temperature on the furnace is controlled using PID. There is master PLC CJ1GCPU45SP which communicates several slaves CJ1MCPU13. It looks that all the PID parameters are send from the master to slaves over DeviceNet using seven DRM21 modules installed on extension rack. I can see where the values for the PID are entered on the HMI and moved to new location in the master but I don't understand why they are not placed in memory locations used by DeviceNet by default as per DRM-21 manual ( which if I understand correctly are D30000 to D31599). Is it because the DRM21 are mounted on extension rack? I will list all the upper limit locations in master, it is a long list but hopefully will help in resolving this issue: HMI entry location Moved to location in the ladder D16401 __________________ D32023 D16403 __________________ D32047 D16405 __________________ D32071 D16407 __________________ D32095 D16409 __________________ D32323 D16411 __________________ D32347 D16413 __________________ D32371 D16415 __________________ D32395 D16417 __________________ D32623 D16419 __________________ D32647 D16421 __________________ D32671 D16423 __________________ D32695 D16425 __________________ D29923 D16427 __________________ D29947 D16428 __________________ D31723 D16429 __________________ D31756 D16430 __________________ D31757 D16431 __________________ D31758 After they are moved to the D3xxxx location they are not used anymore anywhere in the master PLC so I am assuming they are transmitted over to be used in slaves. Is my reasoning correct? How can I calculate address space used by each DRM-21 card to make sure I am understanding what is transferred where? Thank you.

[banker]

Hi Never worked with DeviceNet and omron, but can't you see the address the devicenet card is using in the IO table ? Banker

[BobB]

Perhaps explicit messaging?

[python01]

The problem is that I don't see any instructions for explicit messaging. Just wonder where would the io table be with DeviceNet addressing on Omron?

[banker]

Hi Pyton01 W380E107 and look in the IO table Banker

[python01]

So I did find the DeviceNet allocation tables in the program in question and went through Omron manuals but still do not exactly understand how these are used. For example it says that out block area starts at 7404 and has 38 bytes, the in area starts at 73A0 and has also 38 bytes. But the symbols section does not contain any addresses in these memory locations, or am I looking at the wrong area? What they would be transmitting if these memory locations are not used? I did search the program for the memory locations specified in the DeviceNet settings but could not find any. I am attaching the screen image showing the DeviceNet setup and symbols table behind, can anyone help?

[BobB]

If you use the Windows calculator in Programmer mode - enter the meory areas in HEX and then click DEC and it will convert the data memories fro you. HEX 7404 is 29700 - DM29700. HEX 73A0 is 29600 - DM29600. Hope this helps.

[BobB]

By the way that is not explicit messaging but I/O allocation as far as I can tell - have never done it this way before.

[python01]

Bob, Thanks for your reply, I should have noticed myself that these should be converted to Decimal. Glad you pointed that out. So now I did look into one of the slaves and inblock and outblock areas show start 0 and length 0. So where these values are stored in the slaves? Is it possible they are transferred into the same memory locations as used in master? I am attaching screen shot of the slave DeviceNet configuration.

[PdL]

It;s not really clear to me how your Devicenet network is build up, do I understand correctly you have a CJ1G with DRM21 as Master and seven CJ1M with DRM21 as slave? Normally you would use CX-Integator to define I/O allications between master and slave devices, I never used a DRM21 as slave but a quick check in CX-Integrator shows me the option to set a DRM21 to slave mode and define I/O allocation to another DRM21 set as master. I think this is how your setup is working. You can go online in CX-Integrator and make an upload of the Devicenet network structure and components + parameters, and you should be able to find the allocation. Easiest is to go online with the master CPU first, now open the IO table, right click the DRM21 master unit, and select Start special application with settings inherited. It will open CX-Integrator in online mode and you should be able to drill down to the DRM21 and upload the network structure. See some pics attached.