ProSoft Technology MVI46-PDPMV1 - Manual (Page 66)

Mailbox Messaging MVI46-PDPMV1 ♦ SLC Platform
User Manual PROFIBUS DPV1 Master
Page 66 of 160 ProSoft Technology, Inc.
March 25, 2011
Mailbox Message Structure: To MVI46 module
Byte Offset Type Description
0 Message ID Processor logic or user set. The Message ID field is used
by the MVI46 module to detect a new message in the
PROFIBUS output data image.
When a non-zero value is detected, the message is
processed immediately. The sample ladder logic assigns
specific message IDs to different mailbox messages.
1 Message Info See individual commands for data values to be entered in
each of these register locations.
2 Command
3 Data Size
4 Frame Count
5 Frame Number
6 Offset High
7 Offset Low
8 Extended Word 1
9 Extended Word 2
10 Extended Word 3
11 Extended Word 4
12 Extended Word 5
13 Extended Word 6
14 Extended Word 7
15 Extended Word 8
- See individual
commands
149
4.2.1 Mailbox Message: Set Slave Mode
In addition to station-related user data transfer, which is executed automatically,
the Master can send control commands to a single slave, a group of slaves, or all
slaves simultaneously. These control commands are transmitted as multicast
commands. This permits use of sync and freeze modes for event-controlled
synchronization of the slaves.
The slaves begin sync mode when they receive a sync command from their
assigned Master. The outputs of all addressed slaves are then frozen in their
current state. During subsequent user data transmissions, the output data are
stored on the slaves, but the output states remain unchanged. The stored output
data are not sent to the outputs until the next sync command is received. Sync
mode is concluded with the unsync command.
Similarly, a freeze control command causes the addressed slaves to assume
freeze mode. In this operating mode, the states of the inputs are frozen until the
Master sends the next freeze command. Freeze mode is concluded with the
unfreeze command.