Emerson PACSystems RSTi-EP User Manual

User Manual Section 4
GFK-2958L May 2021
Detailed Descriptions of the Fieldbus Network Adapters 126
Packed process data of the modules
The process data of a digital module are packed directly on the process data of the previous
module. The process data of all other modules always starts with the beginning of the next
word.
Figure 51: Packed Process data in an exemplified module arrangement 4DI, 8DI, 4AI
The module’s process data include a maximum of 494 byte. Therefore, the process data of
assembly 0x65 (101) and 0x66 (102) will include a maximum of 496 byte, whereas the
process data of assembly 0x67 (103) and 0x68 (104) include a maximum of 504 byte. The
actual length is defined by the arrangement of the modules, the assembly’s size is always an
even number of bytes (2 byte, 4 byte etc.). So, in the example assembly 0x65 (101) is 12
byte long whereas
assembly 0x67 (103) is 20 byte long.
Note: The size which is expected during the connection is being established can be read
from class 0x04(4), instances 0x65 to ox68 (101 to 104), attribute 0x04 (4) or via the
web server.
Control Word
8 Bytes of diagnostic data (assembly 0x67) or diagnostic data control word (assembly 0x68)
are attached to the process data of both assemblies. Via the control word (2 byte at the
beginning) and the diagnostic data control word (8 Byte at the end) of the process output
data of assembly 0x68 you can choose which diagnostic data (8 byte at the end) shall be
transferred within the process input data: 0 in the control word chooses diagnostic data, the
1 chooses process alarm
data.
Via the diagnostic control word, you choose the module the data of which shall be
displayed: If there is a 0 in the diagnostic control word, the bits in the process input data
indicate which modules have a diagnostic or a process alarm.
Each bit set indicates an active alarm. If a number from 1 to 64 is written in the diagnostic
control word, the process alarm data (4 byte) or the first 8 byte of the diagnostic alarm
dataset will be transferred within the process input data.
Control
Word
Diagnostics control
word
Diagnostic data
0
0
One bit of each module indicates whether it has a diagnosis
0
1 … 64
Diagnostic data of the set module (the first 8 byte)
1
0
One bit of each module indicates whether it has a process alarm
1
1 … 64
Process alarm data of the set module (4 bytes are being used)

Emerson PACSystems RSTi-EP Specifications

General

Brand	Emerson
Model	PACSystems RSTi-EP
Category	Controller
Language	English