User`s manual

Watlow EZ-ZONE™ Communications • 48 • Chapter 4 DeviceNet
4. As was stated previously, because the PLC platform chosen utilizes a 32-bit word we can see in figure
4.13 that the PM assembly structure will be mapped into 1:I.Data[0 - 20] in the PLC. Recall from our
earlier exercise of registering the PM on the network that there are 84 total input bytes divided by 4
bytes per word which equals 21 words. This represents the T to O assembly structure (see Table 3.6)
where the data is sourced at the target (PM) and sent to the originator (PLC).
5. Clicking on the "Output" tab will yield similar but slightly different results. Different in that there
are a total of 80 output bytes versus 84 for the inputs. Dividing that number by 4 bytes per word we
can see that there will be 20 output words consumed by this module: 1:O.Data[0 - 19]. This will repre
sent the PM O to T assembly structure (see Table 3.7) which is sourced in the PLC (originator) and
sent to the target (PM).
Figure 4.13
Figure 4.12