VEGA VEGACOM 558 Ethernet - Manual (Page 32)

32 VEGACOM 558 Ethernet
High-Byte Low-Byte Maßeinheit Status
Meas. value Add. info
DCS value
Octet 1 Octet 2 Octet 3 Octet 4
Format for transfer of measured values
6.5 Format for transfer of measured
values
Measured values and DCS values
The measured values of the VEGA
processing systems (VEGAMET or
VEGALOG) connected to VEGACOM 558 are
imaged on the input registers of Modicon 584
as described in chapter 6.1 and 6.3. In
VEGACOM 558, they are available for
collection as so-called DCS values.
One DCS value covers two register
addresses, this means that it consists of two
double words, i.e. 4 bytes.
A complete overview of the image of the DCS
values in the input registers of Modicon can
be found in supplement A of this operating
instructions manual.
Structure of a measured value
Measured values of VEGALOG or VEGAMET
are transferred to VEGACOM 558 as signed
data comprising 2 octets. This means, that
the value range is max. +32.768 to -32.767.
Structure of a DCS value
A single DCS value in VEGACOM 558
consists of 4 octets and consists of the
following:
The real measured value has a length of 2
octets and is signed, this means that the
value range is between +32768 and -32767.
In addition to the measured value,
VEGACOM 558 provides one octet per DCS
value for measuring unit and another octet for
information on the actual status of the
measured value.
The octet for the measuring unit is not
presently used and is always filled with the
value zero.
The status describes the condition of the two
associated measured value octets. The
contents of the measured value octet is only
valid if the assigned status has the value
zero.
If you have a status value unequal zero, the
status value and the associated value in the
measured value field must be taken into
account for a detailed failure diagnosis. The
following list explains the possible errors:
Status Meas. Meaning
value
0x00 0xXXXX valid meas. value
0x01 0xXXXX simulated meas. value
(only with VEGAMET
509 and 512)
0x80 0xXXXX old meas. value
(probably interrupted
connection)
0xFE 0x0000 no measured value
available (not
configured)
0xFF 0xFFFF no VEGAMET or
VEGALOG connected
XX = type of error
0xFF 0x8000 failure message of an
individual
measurement loop
Type of error is not
defined