VEGA Modbus-TCP, ASCII protocol - Manual (Page 5)

5
1 Function as Modbus-TCP server
Modbus-TCP, ASCII protocol • VEGAMET 391/624/625, VEGASCAN 693, PLICSRADIO C62
30768-EN-130701
Example of the data of a PC/DCS output
Measured value Status
Register addr. 30001 Register addr. 30002
High-Byte/Low-Byte High-Byte/Low-Byte
The status describes the condition of the associated measured value.
The content of the measured value is only valid if the corresponding
status has the value zero. If there is a status value unequal zero, the
status value and the corresponding value in the measured value field
must be taken into account in a detailed failure diagnosis. The follow-
ing chart explains the possible faults.
Status Measured
value
Meaning
0x00 0xXXXX Valid measured value
0xXX 0x8000 An error number is transmitted in the status
corresponding to the error codes Exx (e.g. 29
= E29 = Simulation).
0xXX 0x00XX An error number which corresponds to the er-
ror codes Exx is transmitted in the status and
in the measured value. Must be configured
via DTM.
Note:
When transmitting the PC/DCS value in Modbus-TCP protocol
(measured value filing as 2 byte short), the decimal point itself is not
transmitted; the value -0.5 bar is transmitted as -50. If a data format
was selected that allows values outside the value range to appear, a
limit is set at the highest value of the value range.
Example: Percent was selected as "Reference value " and #.### as
"Data format ". With this setting, the value 100 % would be transmit-
ted as 100000, which is outside the valid range of max. +32767. This
means that a limit will be imposed and 32767 transmitted instead.
To avoid this, "Data format " #.## should be chosen so that the value
100 % is transmitted as 10000.
Note:
On the switching inputs of PLICSRADIO C62 (measurement loops
4 … 6) the values 0 (switch open) and 100 (switch closed) are trans-
mitted as measured values; the units are discarded.
The switching conditions of the relay are transferred as bit information.
The following equivalencies apply to the switching relays:
•
0 = Switching status Off
•
1 = Switching status On
The following equivalencies apply to the fail safe relay:
•
0 = Failure message Off, relay switching condition On
•
1 = Failure message Off, relay switching condition Off
The following chart shows the addressing of the temporary memory
via Modbus.
Filing of the relay values