Rockwell Automation 1738-ADNX ArmorPoint I/O DeviceNet Adapters - Manual (Page 45)

Publication 1738-UM001A-EN-P - February 2005
Use Auto Start Mode 3-3
How Is I/O Data Mapped Using Auto Start Mode?
In Auto Start Mode, you can map I/O data in the adapter’s memory in
one of the following ways:
• Byte Boundaries
• Word Boundaries
• Double Word Boundaries
• Fixed Boundaries
Byte Boundaries
Each node’s I/O data is mapped in the adapter’s memory at the next
available byte. This option works best in applications that use
Allen-Bradley PLCs and SLCs.
Word Boundaries
Each node’s I/O data is mapped in the adapter’s memory at the next
available word. This option works best in applications that use
Allen-Bradley PLCs and SLCs.
Double Word Boundaries
Each node’s I/O data is mapped in the adapter’s memory at the next
available double word. This option works best in applications that use
Allen-Bradley Logix products.
Fixed Boundaries
The map to the fixed location is based on the node address. Mapping
size ranges from 1 to 32 and is set using an EDS parameter. The
mapping for a node with address 1 begins on byte 2. The formula for
mapping is: 2+((N-1)(mapsize)), where N = node address.
Keep the following in mind when using fixed boundaries:
• You specify fixed map size using EDS parameters
• Data is mapped after status/channel words in I/O image,
beginning with byte 2
• No data area is reserved for MACID 0 (the adapter)