Watlow Series D8 - Manual (Page 78)

Chapter 3: Communicating by DeviceNet Series D8 User’s Guide
60 Watlow Anafaze Doc. 0600-3120-2000
To determine the integer value to set in the controller, move
the decimal to the right the number of places specified.
For example:
•
If a loop has a process input with a display format of
-99.99 to 300.00, values are stored with two decimal
places. If you read a value in the set point register of
2500, you should interpret that value as 25.00.
• If a loop has a thermocouple input and you want to set the
Alarm High SP
parameter to 355 through logic, you
should set a value of 3550.
Decimal Placement for Percentage Values
Percentage values are stored internally in tenths of a percent,
such that 1000 corresponds to 100.0 percent. Divide values by
ten when reading, and multiply values by ten before writing.
D8 DeviceNet Overview
The D8 controller is configured as a Group 2 Only Slave de-
vice using the Predefined Master/Slave Connection Set.
The D8's DeviceNet interface includes objects in two main
categories, DeviceNet Objects and Application Objects. De-
viceNet objects handle what is necessary for networking and
communications. Application Objects provide access to the
D8 controller's parameters and data.
Master/Slave Connections
The D8 supports the Predefined Master/Slave Connection Set,
which calls for the utilization of an Explicit Messaging Con-
nection to manually create and configure Connection Objects
within each connection end-point. These Connections are re-
ferred to collectively as the Predefined Master/Slave Connec-
tion Set
.
The master is the device that gathers and distributes I/O data
for the process controller. Slaves are the devices from which
the master gathers I/O data and to which the master distributes
I/O data. The master “owns” the slaves whose node addresses
appear in its scan list. To determine which slaves it will com-
municate with, the master examines its scan list and sends
commands accordingly. Except for the Duplicate MAC ID
Check, a slave cannot initiate any communication before be-
ing told by the master to do so.