Data Processing/Order Of Operations For Fixed Assembly Blocks - Emerson Control Techniques Epsilon Ei Reference Manual

Data Processing/Order of Operations for Fixed Assembly Blocks

Since the transfer of parameters over the DeviceNet network has the potential to transfer on
the same scan of the PLC, the user needs to take special consideration of the order of bits sent.
When the Master sends two or more bits in the same DeviceNet message, the bits get
implemented in the Ei-DN in the following order:
• Get Master Send Data Pointer
• Process Master Send Data Block (update word information)
• Process Master Send Bits **
• Send Input data to Master Receive FAB
**The following list represents the priority/order of bit data processed (first to last) sent from
the Master.
• Stop Bit (Held until clear)
• Home Bits (Initiate a home)
• Index Bits (Initiate an Index)
• Jog Bits (Held until clear)
** If individual bits are changed simultaneously within each of the above group, the order of
processing shall follow:
1. Home Bits
• Home Initiate
• Define Home
2. Index Bits
• Index Select
• Index Initiate
3. Jog Bits
• Jog +
• Jog-
• Jog Fast
Note
An Implicit Poll initiates motion, and an immediate response is sent. This response does
not wait for motion to complete, i.e., an Index Initiate Command sent before the drive
completes an index will not be acknowledged by the drive.
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Configuring the DeviceNet Network
17