Owner's manual
Table Of Contents
- Foundation™ Fieldbus Blocks
- Foundation™ Fieldbus Technology and Fieldbus FunctionBlocks
- Analog Input (AI) FunctionBlock
- Analog Output (AO) Function Block
- Arithmetic Function Block
- Discrete Input (DI) Function Block
- Discrete Output (DO) Function Block
- Integrator (INT) FunctionBlock
- Input Selector (ISEL) FunctionBlock
- Proportional/Integral/Derivative (PID) Function Block
- Signal Characterizer (SGCR) Function Block
- Diagnostics (ADB) Transducer Block
- Applications
- Analog input (AI) Function Block
- Analog Output (AO) Function Block
- Arithmetic (ARTH) Function Block
- Discrete Input (DI) Function Block
- Discrete Output (DO) Function Block
- Input Selector (ISEL) Function Block
- Integrator (INT) Function Block
- Proportional/ Integral/Derivative (PID) Function Block
- Signal Characterizer (SGCR) Function Block
- Index
5-3
Discrete Input (DI) Function Block
Field Value Processing You can configure the Invert I/O option (IO_OPTS) to process
FIELD_VAL_D. The invert option indicates whether or not the discrete
input is logically inverted before it is stored in the process variable
(PV_D).
The output of the Invert processor is PV_D. This value goes to the mode
switch where it becomes OUT_D when the mode is Auto. OUT_D is also
tested for an alarm state. You might choose this option when the field
contact is normally closed, so an open contact or a broken wire
represents the active state of the condition being sensed.
NOTE
Invert is the only I/O option that the DI block supports. You can set the
I/O option in Manual or Out of Service mode only.
Alarm Detection To select the state that initiates an input alarm, and to set discrete
alarm substatus in the output, configure the DISC_LIM attribute. You
can enter any value between 0 and 255. A value of 255 disables the
alarm.
Block Errors The following conditions are reported in the BLOCK_ERR attribute:
Simulate active – SIMULATE_D is enabled; OUT_D does not reflect
actual process conditions.
Input failure/process variable has Bad status – The hardware is
bad, the configured channel is invalid, or a Bad status is being
simulated.
Out of service – The block is not being processed.
Modes The Discrete Input function block supports the following modes:
Manual (Man) – The output (OUT_D) is disconnected form the field.
Automatic (Auto) – The block algorithm determines OUT_D.
Out of Service (O/S) – The block is not processed. The output status is
set to Bad: Out of Service. The BLOCK_ERR attribute shows Out of
Service.
Status Handling Under normal conditions, a Good: Non-cascade status is passed through
to OUT_D. The block also support Status Action on Failure and Block
Error indications.
Action on Failure In case of hardware failure, FIELD_VAL_D, PV_D, and OUT_D change
to a Bad status and the BLOCK_ERR attribute displays Bad PV. When
SIMULATE_D is enabled, FIELD_VAL_D, PV_D, and OUT_D change
to a simulation status. When the block is set to Man mode, OUT_D is
set to Good: Non-cascade, Constant status.