ILX69-PBM ♦ CompactLogix™ or MicroLogix™ Platform
Annex
PROFIBUS Master Communication Module
User Manual
ProSoft Technology, Inc.
Page 109 of 113
Watchdog
Using the Watchdog functionality, a network slave is able to monitor bus traffic. This
ensures that the ILX69-PBM is still active, with process data still being updated. The
Watchdog time is configured in ProSoft fdt Configuration Manager and is transmitted
from the ILX69-PBM to the slave during the network start-up phase. If the Watchdog
timeout has been reached, the slaves go to their Fail Safe state (if supported) or set their
outputs to "0".
9.1.2 DPV1 Services
As an addition to cyclic DPV0 services, acyclic services called Read, Write and Alarm
were added to PROFIBUS. These services are referred to as DPV1. With DPV1, it is
possible to address individual slaves within the network. In addition, DPV1 services
allow the transfer of non-time critical data to slaves. DPV1 data exchange takes place
after cyclic data exchange in a PROFIBUS network cycle.
Read Request
With a Read Request message, the ILX69-PBM can read data addressed by slot and
index within the data range of a slave device. This may take several DPV0 cycles. If the
ILX69-PBM discovers a timeout, it aborts both DPV1 and DPV0 communication with the
slave. The communication to the slave must be re-established. The ILX69-PBM initiates
the Read Request service.
Write Request
With a Write Request message, the ILX69-PBM can write data to a slave, addressed by
slot and index. The timeout handling is identical to the Read Request. The ILX69-PBM
initiates the Write Request service.
Alarm Indication
DPV1 Alarm handling is an addition to the Device Diagnostics function in a PROFIBUS
message. Alarms are reported to the ILX69-PBM as device-specific diagnostics
information. The slave initiates an Alarm Indication. Other than Device Diagnostics
messages, Alarms must be acknowledged by the ILX69-PBM.
Start/Stop Communication
PROFIBUS communications can be started/stopped by using the "NRDY" (NotReady)
Bit. When this bit is set, the communication between the ILX69-PBM and all slaves is
stopped. All slaves will clear their outputs and the ILX69-PBM will be in stop mode. This
control bit allows the user program to make a controlled start of the communication with
the PROFIBUS network.
