Modifying implicit assembly members, Profibus dp - (decentralized peripherals) – Watlow EZ-ZONE PM User Manual
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Watlow EZ-ZONE
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PM Limit Controller
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Chapter 8 Features
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 "
") 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
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.
Profibus DP - (Decentralized Peripherals)
This protocol is typically used to operate sensors and actuators via a centralized controller within industrial-
ized production topologies. Data rates up to 12 Mbit/s on twisted pair cables and/or fiber optics are possible.
This protocol is available in three functionally graded version; DP-V0, DP-V1 and DP-V2. It should be noted
that Watlow products utilizing this protocol support DP-V0 and DP-V1 only.
DP-V0 - provides the basic functionality of DP, including cyclic data exchange, station, module and channel
specific diagnostics and four different interrupt types for diagnostics and process interrupts.
Cyclic Data refers to input/output data that is pre-configured to pass from the Profibus-DP Class 1 Master
and the Slave at a known rate. Cyclic data is expected on both the sender and the receiver end of the mes-
sage.
Note:
To use DP-V0 (cyclic data transfer) first configure and then register the General Station Description (GSD)
file. Watlow provides a software tool allowing for total customization of the data to be read and or written
to. Acquire this software tool (Profibus GSD Editor) via the CD that shipped with the product or, as an al-
ternative, point your browser to:
vigate to
the bottom of the page and click on "Software and Demos" to download the software.
Using the GSD Editor a user can configure up to a maximum of 135 different parameters that can be read or
written to from Zone 1 through 16.
DP-V1 - contains enhancements geared towards process automation, in particular acyclic data communication
for parameter assignment, operation, visualization and interrupt control of intelligent field devices, in con-
junction with cyclic user data communication.
Acyclic Data is a message that can be sent and or received at any time where they typically have a lower pri-
ority then cyclic messages. This type of messaging is typically used for the purpose of configuration or per-
forming some sort of a diagnostic function.