What are the statuses of PRD and ROUT in the instrument status?
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What are the statuses of PRD and ROUT in the instrument status? Also, what is the difference between RCAS and CAS?
There are nine different basic types of state modes for basic functional blocks. The following table lists the operating modes of the basic blocks:
| Symbol | Name | Definition |
|--------|------|------------|
| O/S | Exit operation | All functions become inactive. |
| IMAN | Initialization | Manual control; calculation and output operations are stopped. |
| TRK | Tracking | Forces the output to a specified value; calculation operations are stopped. |
| MAN | Manual output | A value is manually entered; calculation operations are stopped. |
| AUT | Automatic | Performs calculation operations and outputs the results. |
| CAS | Cascade | Uses the set variables provided by higher-level blocks to perform calculation operations and output the results. |
| PRD | Direct output by the master controller | The set variables provided by the upstream blocks in the cascade system are used directly as output values; calculation operations are stopped. |
| RCAS | Remote cascade | Uses remote set values from the upper-level supervisory computer as set variables to perform calculation operations and output the results. |
| ROUT | Remote output | Uses remote set values from the upper-level supervisory computer as set variables for direct output; calculation operations are stopped. |
1. Direct output by the master controller (PRD): When the downstream loop of a cascade system becomes uncontrollable due to input errors, the results of the calculation operations performed by the upstream controller are used directly as control signals for the valves. This operating mode is known as direct output by the master controller (PRD). 2. Remote output (ROUT): In the remote output mode, the control block in the FCS station receives the control calculation results generated by the upper-level monitoring computer – the remote operation variables (RMV) – and outputs them as operation variables (MV). 3. Cascade (CAS) uses the set variables provided by the higher-level block to perform control calculations and outputs the results of these calculations. 4. Remote Cascade (RCAS) operates in a remote output mode; the conventional control blocks in the FCS station receive the control calculation results generated by the higher-level monitoring computer, which are used as set variables (RSV). The RSVs are then used to carry out control calculations and produce the corresponding results.
| Symbol | Name | Definition |
|--------|------|------------|
| O/S | Exit operation | All functions become inactive. |
| IMAN | Initialization | Manual control; calculation and output operations are stopped. |
| TRK | Tracking | Forces the output to a specified value; calculation operations are stopped. |
| MAN | Manual output | A value is manually entered; calculation operations are stopped. |
| AUT | Automatic | Performs calculation operations and outputs the results. |
| CAS | Cascade | Uses the set variables provided by higher-level blocks to perform calculation operations and output the results. |
| PRD | Direct output by the master controller | The set variables provided by the upstream blocks in the cascade system are used directly as output values; calculation operations are stopped. |
| RCAS | Remote cascade | Uses remote set values from the upper-level supervisory computer as set variables to perform calculation operations and output the results. |
| ROUT | Remote output | Uses remote set values from the upper-level supervisory computer as set variables for direct output; calculation operations are stopped. |
1. Direct output by the master controller (PRD): When the downstream loop of a cascade system becomes uncontrollable due to input errors, the results of the calculation operations performed by the upstream controller are used directly as control signals for the valves. This operating mode is known as direct output by the master controller (PRD). 2. Remote output (ROUT): In the remote output mode, the control block in the FCS station receives the control calculation results generated by the upper-level monitoring computer – the remote operation variables (RMV) – and outputs them as operation variables (MV). 3. Cascade (CAS) uses the set variables provided by the higher-level block to perform control calculations and outputs the results of these calculations. 4. Remote Cascade (RCAS) operates in a remote output mode; the conventional control blocks in the FCS station receive the control calculation results generated by the higher-level monitoring computer, which are used as set variables (RSV). The RSVs are then used to carry out control calculations and produce the corresponding results.