With a DeviceNet 1769 SDN Scanner, a Micro 1500, and 4 EC3+ overloads:

The 1769 I/0 maps into the Micro 1500 with an input size of 82 words.
Is the size of the mapped input fixed?
With four EC3+, is the input for each 20 1/2 words?

The ouput is only 4 words.

It just seems like a lot of inputs for each EC3+.
Thanks for your help this is my first DeviceNet Project.

I'm not familiar with the EC3 overloads, but the mapping/sizing of the I/O for the devicenet should be configured using rsnetworx for devicenet. With this, you should be able to manually configure the size of the mapped I/O for the devices on the network.

The E3+ overload relay has a Consumed Data size of 1 byte (this is Output data from the controller).

By default, the Produced Data connection is 8 bytes. This is Input data to the controller.

The Produced Data connection (again, the default) consists of an assembly of Parameters 21, 1, 2, and 3.

For a network consisting of a scanner and four E3+ overloads, your Input data map would take up 16 words and your output data map would take up only 2 words (I prefer to space them out, 1 per Word, and take up 1 word per device).

Search in the RSNetworx program files folder for PowerPoint Slideshow (*.pps) files and go through the introductory tutorial about the basics of using RSNetworx for DeviceNet.

You can put any of the fifteen or so "monitoring" parameters into the Input Assembly by pointing to their parameter numbers using Parameters 61,62,63,64.

I often build the Input Assembly with parameters 21, 14, 15, and 4. This gives you the overall Status, the Warning Code, the Trip Code, and the Average Current.

If any of the values in Parameters 61,62,63,65 are zero, the Assembly is reduced in size to the number of valid parameter pointer values, starting with parameter 61. I've done systems where we left 63 and 64 at zero and only used two parameters per E3+. We did that because there were 40 or so overloads in a single network with a SLC scanner.

I think the 1769-SDN I/O size is changeable, if you have a packed Compact backplane and need to free up I/O memory in the controller.