ProSoft Technology PS69-DPM - Manual (Page 108)

Contents PS69-DPM ♦ CompactLogix or MicroLogix Platform
User Manual PROFIBUS DPV1 Master
Page 108 of 130 ProSoft Technology, Inc.
October 1, 2014
Specification Description
Agency Certification:
UL/CE C-UL certified, UL 508 listed, CE
PROFIBUS conformance certified
6.2 PROFIBUS Functionality
6.2.1 DPV0 Services
DPV0 services in PROFIBUS refer to the cyclic data exchange mechanism between a class
1 master and a network slave. PROFIBUS-DP defines two types of masters. The class 1
master handles data communication with slaves assigned to it. A class 2 master should only
be used for commissioning purposes. In a PROFIBUS telegram, class 1 masters and slaves
transmit up to 244 bytes per telegram. Valid station addresses on PROFIBUS range from 0
to 126.
Fail Safe Mode
For safety reasons, the PROFIBUS master informs connected slaves of its current control
status at certain intervals using a "Global Control" telegram. If the master goes to Clear
Mode, the Fail Safe enabled slaves will switch to a Fail Safe state. Slaves capable of the
Fail Safe state can be configured to either to hold the last state of the outputs or set its
outputs to "0". Slaves that do not support the Fail Safe state set their outputs to "0".
Global Control
With the Global Control telegram, the master can send unsolicited commands like
Sync/Unsync, Freeze/Unfreeze and Clear Data to a slave or a group of slaves for
synchronization purposes. Group membership is defined during network start-up and can be
set in PROSOFT.fdt (SYCON.net).
Sync and Freeze
Sync and Freeze are optional commands and slaves do not need to support them. However,
they must be able to process the Global Control telegram. With a Freeze command, the
master prompts a slave or a group of slaves to "freeze" their inputs to the current state. A
Sync telegram causes the current output data to latch at their current state until the next
Sync telegram arrives. Unfreeze and Unsync cancel each corresponding state.
Extended Device Diagnostics
Using diagnostic telegrams, the slave informs the network master of its current state in a
high-priority telegram. The first 6 bytes of the diagnostic telegram are comprised of
information such as its identity code ("Ident Code") or correct/incorrect configuration. The
remaining bytes of this telegram are referred to as Extended Device Diagnostics and they
contain information that is specific to the particular slave.