ProSoft Technology PTQ-PDPMV1 - Manual (Page 156)

Mailbox Messaging PTQ-PDPMV1 ♦ Quantum Platform
User Manual PROFIBUS DP Master Network Interface Module for Quantum
Page 156 of 306 ProSoft Technology, Inc.
August 12, 2014
Please keep the following key points in mind:
 If no message is to be sent in the mailbox, the Message ID value in the
Output Image must be set to zero (0).
 The PTQ module will set the Last Out Mailbox Message ID value in the Input
Image to zero (0).
 The Message ID field is used by the PTQ module to detect new outgoing
messages. When the value is detected as non-zero, the PTQ processes the
message immediately.
 The Message ID should be changed for each new outgoing mailbox
message. A simple zero-to-one toggle scheme can be used, or an
incrementing register value can be used (1 to 15).
 When a new message is to be sent:
a Copy or set up the message contents (keep Message ID value at zero) to
the Output Data locations.
b Set the Message ID value to PTQ module.
 After the PTQ module processes the Outgoing Mailbox command, the PTQ
will set the Last_Out_Mailbox_Message_ID in the Output Data image to
match the outgoing Message ID in the Output image. This event on the
processor side can be used by the processor logic to clear the outgoing
Message ID if desired.
6.2.1 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 at 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.
Note 1: It is only possible to send control commands when operating mode is either CLEAR or
OPERATE.
Note 2: Not all slaves support this feature. Refer to the documentation for the actual slave for more
information.