ProSoft Technology MVI56-PDPMV1 - Manual (Page 135)

MVI56-PDPMV1 ♦ ControlLogix Platform Mailbox Messaging
PROFIBUS DPV1 Master User Manual
ProSoft Technology, Inc. Page 135 of 255
March 22, 2011
3.2 Flex Mode Mailbox Communication
The processor sends a MSG instruction to the module with a Set Attribute Single
type to request the module to process a mailbox function.
When the module has a response ready to be processed, it will latch bit 15 of the
CIP Mailbox MSG Index word of the input block. The ladder logic recognizes this
condition and sends another MSG instruction (now Get Attribute Single) to
retrieve the mailbox response from the module: