Siemens 7XV5673 Device Manual page 146

8 Communication
8.2 Modbus
8.2.7.2 Data Type - Indications (Read Only)
The Indications data type is represented by 2 bits in holding registers
Q V
In d ica tio n 8
Where:
• Q: Status/quality bit: 0 = OK, 1 = invalid
• V: Value bit: 0 = OFF, 1 = ON
Status or Quality Bit "Q"
An indication is invalid if the result of a calculation is based on an invalid value. In the case of an invalid indica-
tion, the quality bit is set to "1". The value bit can be ignored in this case.
Example: "Indications from remote" are invalid until they are set via communication. In the case of
communication failure, they automatically become invalid again.
For indications that are always valid, for example the internal device indication Device OK, "0" is transmitted
as the quality bit.
Value Bit "V"
The value bit indicates whether an indication is ON (=1) or OFF (=0).
8.2.7.3 Data Type - Controllable Indications/Commands (Read/Write)
The Controllable Indications data type is needed for:
• The binary outputs of the SICAM I/O Unit (Indications from Remote)
• Execution of device internal commands (for example resetting of counter)
The holding register is used for read and write access in this context..
Use as Read Register
Q V
In d ica tio n 8
Where:
• Q: Status/quality bit: 0 = OK, 1 = invalid
• V: Value bit: 0 = OFF, 1 = ON
See also chapter 8.2.7.2.
146
Q V Q V Q
In d ica tio n 7 In d ica tio n 6 In d ica tio n 5
e.g. Holding register 0101
Q V Q V Q
In d ica tio n 7 In d ica tio n 6 In d ica tio n 5
Holding register 0141
V Q V Q V
In d ica tio n 4 In d ica tio n 3
V Q V Q V
In d ica tio n 4 In d ica tio n 3
SICAM I/O Unit, 7XV5673, Device Manual
E50417-H1040-C484-A3, Edition 05.2012
Q V Q V
In d ica tio n 2 In d ica tio n 1
Q V Q V
In d ica tio n 2 In d ica tio n 1