ProSoft Technology 5204-DFNT-PDPMV1 - Manual (Page 75)

PDPMV1 ♦ ProLinx Gateway Mailbox Messaging
PROFIBUS DPV1 Master Protocol Manual
ProSoft Technology, Inc. Page 75 of 157
March 23, 2011
3 Mailbox Messaging
In This Chapter
Mailbox Message Queuing .................................................................... 76
Special Function Mailbox Messaging Commands ................................. 77
Mailbox Messaging Error Codes ........................................................... 99
The PDPMV1 PROFIBUS DP Master uses a process called Mailbox Messaging
to exchange parameter data between the processor, Master, and slave devices.
This process provides a way to encapsulate and prioritize commands and data
sent between the PROFIBUS Master and slaves.
The PROFIBUS DP-V1 protocol specifies two types of data transmission
messages (telegrams): Cyclic Data Telegrams and Acyclic Data Telegrams.
Cyclic data communication is the exchange of normal slave input and output (I/O)
data and is handled automatically by the Master in a defined, recurring,
deterministic sequence based on the configuration you create in ProSoft
Configuration Builder (PCB).
Acyclic communication extends data communication beyond normal I/O data to
allow moving field device parameterization and calibration data over the bus
during runtime and to allow for extended diagnostics and alarm messages.
Acyclic data telegrams are transmitted in the gaps between cyclic data telegrams
and, therefore, have a lower priority and get less bandwidth than cyclic data.
Mailbox Messaging commands are incorporated into the sample ladder logic.
Mailbox messages and responses to mailbox messages are stored in mailbox
data types.
The following chapter discusses these features in more detail.