User`s manual

Watlow EZ-ZONE™ Communications • 52 • Chapter 4 DeviceNet
Sending Data From PLC to PM via Ladder Logic
In figure 4.21 two copy instructions are used to move the data to and from the PM via the PLC logic.
Figure 4.21
Changing the Default Assembly Structure in the PM
In figure 4.17 there were three members of the T to O assembly identified as not used due to the PM
model used. As an example, lets change the default assembly of the fourth member (currently identified as
"PMDnet_T_to_O.AIN_2_PV"), to "Autotune Set Point". Step-by-step, we will now look at what is required to
change the default assembly for the third member with the status word being member 0. This same logic with
some minor modifications can be used to modify any member of either assembly, input or output.
1. In figure 3.3g find the class, instance, and attribute that needs to be changed. In this case, because the sta
tus word is not shown (member 0) we will need to redefine Class 119, Instance 2, and Attribute 3.
2. Find the parameter "Autotune Set Point" in the Operations Page of this manual to acquire the class, in
stance, and attribute (CIA) information. In this case, the CIA is 151, 1, and 20 respectively. Figure 4.23
shows the hexadecimal equivalent of 97, 1, and 14.
Keep in mind that in the example below that it is the T to O assembly that will be modified. The user will
be able to see what the current Autotune Set Point is as it is currently in the PM. If it is desired to be able to
change the Autotune Set Point via the PLC then similar logic would need to be created to modify the O to T
assembly as well. In fact, all that is really needed is that the instance identified in the MSG instruction below
be changed to one instead of two and then modify the attribute desired. As can be seen in figure 3.3f instance
one of class 119 represents the O to T assembly where instance two represents the T to O (figure 3.3g).
Figure 4.22