Hi Everyone,

I have a specific problem when trying to change the parameters on a DNI module used on my project's DeviceNet network.

When I tried, earlier on today, to change the input/output file number and the input/output word offsets in the parameter list for that node, I received an error message: "Error occurred when communicating with device." (I was using RSNetWork for DeviceNet, and was not online when making the alterations and trying to download the new settings).

I was trying to change parameter numbers 1, 2, 4, 5, 6, 7, 9 and 10.

The previous (factory-programmed) input file number for the equipment was N20. I need it to be N60. I realise that my series B DNI requires the number of input/output words to be 2, so I kept this setting. I left the input word offset at 0.

For the output word number, I need (N)61, offset 0, number of words 2.

But every time I try to download the changes to the DNI, the error message appears and the changes are not allowed.

Any help would be appreciated. By the way, I'm "viewing" the DeviceNet network in RSNetWorx for DeviceNet, via a 1770-KFD.

Thanks,

Richard Byrne.

I think it's a Net-DNI rule that you can't change the DF1 target files or offsets while the DF1 automatic read/write feature is in RUN mode.

The Series A and Series B versions did this a little differently.

Series A had a "DNI Mode" parameter that you had to purposely change from "Operational" to "Disabled" before you could make a change. This was the last parameter, #17.

Series B defaults the "I/O Scan Enable" to Disabled, so you can make these changes while initially setting up the module, then put it into Run mode later. This is Parameter 12 on the Series B device.

The Net-DNI is a neat little device. I think it ought to be built into a MicroLogix 1100D, but then that's what I get for drinking beer with SLC designers.

I re-read your list of parameters you were trying to change, and that adds another factor.

You can't change the size of an I/O connection while it's in the Established mode. This includes changing parameters that affect the size of the I/O connection.

You can disable the Connection in the scanlist, or remove it totally. Most of the time you also have to cycle power on the slave device.

I run into this a lot with FLEX I/O. Usually I have to go to Program Mode on the controller as well as cycle power on the FLEX rail.

Thanks for the help Ken. I've not been able to progress on my project because of this problem. Hopefully we'll be flying again.

Let me just make sure I understand what you're telling me...

You're exactly correct on how to set the Net-DNI/B into "disabled" DF1 file scanning so you can change the DF1 file numbers.

In order to change the Poll/Explicit file Split point, or change the I/O file Size (both of which change the size of the I/O Connection), the I/O connection will have to be logically broken.

Open up the 1747-SDN properties in RSNetworx, and go to the scanlist configuration window and highlight the Net-DNI/B.

You should see a check mark for "Active" for the scanlist entry, right above the Electronic Keying check boxes.

Uncheck that (you will probably have to put the SLC in Program mode) and power cycle the Net-DNI, and that will break the I/O connection.

When the Net-DNI powers back up, the 1747-SDN will not try to make an I/O connection to it, so you will be free to change the parameters in the DNI that change the I/O connection sizes.

You will probably have to change the I/O Connection size and re-map the DNI in the 1747-SDN's scanlist if you change the file sizes.