Communication
ILX69-PBM ♦ CompactLogix™ or MicroLogix™ Platform
User Manual
PROFIBUS Master Communication Module
Page 72 of 113
ProSoft Technology, Inc.
The alarm indication registers start with the byte "Alarm_Status". This byte is a collection
of bits to indicate alarm status. Bit D0 (AlarmInd) is set to "1" to alert the user application
that an alarm request has been received by the ILX69-PBM.
The specifics of the alarm request are in the remaining alarm indication fields. It contains
the slave station address "Rem_Add", the slot number "Slot_Number", etc. according to
the PROFIBUS specification. If an alarm is indicated, the user application must decide
what to do.
The application must respond to the alarm with a CIP message, described later in this
manual. With its response to the slave, the user application confirms that the alarm was
received. When the application responds to the alarm using a CIP message, Bit 0 will be
set to "0" indicating that the alarm has been acknowledged and is no longer pending.
The alarm information Rem_Adr, Slot_Number, etc. is not cleared.
It is possible that multiple alarms are pending. In this case, bit D0 will not be reset to "0"
when the application has responded to one alarm. Only the alarm information Rem_Add,
Slot_Number etc. will be updated in the case of multiple alarms pending.
To handle this situation, the application must also monitor the variable "AlarmCnt". This
counter will be incremented every time a new alarm is pending.
Note:
It is possible to receive several alarms from one or more slave. The
ILX69-PBM has a buffer for only 32 alarms. The application must respond
as fast as possible to alarms.
If the internal alarm buffer runs over, further alarms are lost. This situation
is indicated by the "Alarm_Status" bit D7 "AlarmOverrun". If an alarm was
lost, this bit is set to "1". It will be cleared only if the bus communication is
stopped.
For example, if the controller stops or the application stops, the bus
communication by the NRDY bit in the command register will trigger.
PROFIBUS Input Data
Bytes 88 to 495 is used for PROFIBUS input data received from the slaves. The input
data is transferred from the module to the controller. Input data from the PROFIBUS
system always starts at the 88th Byte (based on start index 0) in the input region. Thus,
the module has a maximum of 408 bytes input data (496 byte input region
– 88 byte
status).
The input data of the slaves are linear corresponding to the I/O Mapping assigned by
ProSoft fdt Configuration Manager. ProSoft fdt Configuration Manager is capable of
configuring more than 408 Bytes of input data. Should the input data of the system
exceed 408 bytes, the module and the sample ladder logic (AOI) will page the data until
all the PROFIBUS Input data has been transferred.
