Owner manual

Watlow EZ-ZONE
®
PM Integrated Controller • 143 • Chapter 9 Features
Note:
If the control is brought back to the factory defaults the user configured assemblies will be overwritten.
Note:
The maximum number of implicit input/output members using DeviceNet is 200. When using EtherNet/IP
the maximum is 100.
CIP Implicit Assemblies
Communications using CIP (EtherNet/IP and DeviceNet) can be accomplished with any PM Integrated con-
trol equipped with either DeviceNet or EtherNet/IP communications cards. As was already mentioned, read-
ing or writing when using CIP can be accomplished via explicit and or implicit communications. Explicit com-
munications are usually executed via a message instruction within the PLC but there are other ways to do
this as well outside of the focus of this document.
Implicit communications is also commonly referred to as polled communications. When using implicit
communications there is an I/O assembly that would be read or written to. The default assemblies and the
assembly size is embedded into the firmware of the PM control. Watlow refers to these assemblies as the T
to O (Target to Originator) and the O to T (Originator to Target) assemblies where the Target is always the
EZ-ZONE PM controller and the Originator is the PLC or master on the network. The size of the O to T as-
sembly is initially set to 20 (32-bit) members where the T to O assembly consists of 21 (32-bit) members. All
assembly members are user configurable with the exception of the first T to O member. The first member of
the T to O assembly is called the Device Status, it is unique and cannot be changed. If the module has been
properly configured when viewing this 32-bit member in binary format bits 12 and 16 should always be set
to 1 where all of the other bits should be 0. The 20 members that follow Device Status are user configurable.
The Appendix of this User's Guide contains the PM implicit assemblies (See Appendix: CIP Implicit Assembly
Structures).
Compact Assembly Class
Along with the standard implicit assembly where each module parameter (member) occupies one 32-bit as-
sembly location there is also a Compact Class assembly. The need for the Compact Class assembly members
became apparent as the number of member instances grew with the EZ-ZONE family of controls. Because
there is a limited number of implicit assembly members (20 input, 20 output), the Compact Class enables the
user to modify the standard assembly offering to their liking while also achieving much better utilization of
each bit within the 32-bit member. As an example, if a standard Implicit Assembly member were configured
to monitor Alarm State 1 the entire 32-bit member would be consumed where just 7 bits out of the 32 will be
used to reflect: Startup (88), None (61), Blocked (12), Alarm Low (8), Alarm High (7) or Error (28) for Alarm
1 only. With Compact Class assembly member 12 (identified in this document as "12 A Alarm Read") in use,
the alarm states of all 4 alarms can be placed in one 32-bit assembly member using just 2 bits for each state.
Bits 0 and 1 would represent Alarm State 1, bits 2 and 3 Alarm State 2, etc... Each pair of 2 bits can repre-
sent the following states: 00 = None, 01 = Alarm Low, 10 = Alarm High and 11 = Other. There is a variety of
predefined Compact Class members that can be used (See Appendix: Compact Class Assembly Structure) to
modify the default implicit assemblies.
Note:
As is the case with any available parameter within the PM control the Compact Class members can also be
read or written to individually via an explicit message as well.
Modifying Implicit Assembly Members
To change any given member of either assembly (T to O or O to T) simply write the new class, instance and
attribute (CIA) to the member location of choice. As an example, if it were desired to change the 14
th
mem-
ber of the T to O assembly from the default parameter (Cool Power) to the Compact Class 12
th
member (See
Appendix: Compact Class Assembly Structure) write the value of 0x71, 0x01 and 0x0C (Class, Instance and
Attribute respectively) to 0x77, 0x02 and 0x0D. Once the change is executed, reading this member location
(as was discussed above) will return the Alarm States (1-4) to paired bits 0 through 7 where 00 = None, 01 =
Alarm Low, 10 = Alarm High and 11 = Other.
The CIP communications instance will always be instance 2.