The SLPC Programmable Indicating Controller is a microprocessor based user-programmable instrument, which provides signal computation and control functions as well as sequence logic functions.
In addition to simple PID control, Batch control and Sample and hold PI control, the SLPC’s control functions include variable gain control and dead time compensation control and a single SLPC can simulate two controllers in a cascade control or auto selector control configuration.
There are about 46 types of computational and logic functions which can be freely combined to create user-defined functions.
FUNCTIONS:
• A new “expert-system” self-tuning mode automatically optimizes PID parameters.
• A user-adjustable set point filter, used to improve the response to set point changes, also provided as a standard feature.
SPECIFICATIONS:
Input/output:
Analog Input : 1 to 5v DC, 5 points.
Analog Output: 1 to 5v DC, 2 points.
4 to 20mA DC, 1 point.
INDICATION:
Process variable and Set point indicator:
Dual pointer moving coil meter or fluorescent bar graph indication plus a four digit numeric display.
Output indicator: Moving coil type.
Manual output operation: Two- speed lever action.
Programmable function key (PF key): 1 Key (which can be used as status input signal).
CONTROL FUNCTIONS:
Basic Control Module: A single control module.
Cascade Control module: Two control modules connected in cascade. SLPC controller can implement a cascade controller. An arithmetic computation may be performed between primary and secondary controllers.
Signal Selector Control Module: Two control modules connected in parallel. One SLPC controller can implement an auto selector control loop.
SLPC FEATURES:
SLPC features include the following:
• The SLPC front panel resembles that of a conventional analog controller so it is easy to use.
• SLPC parameters can be changed using a side-panel display and keyboard .The display shows a mnemonic alphabetic code representing the parameter name and the corresponding numeric value of the parameter, in engineering units.
• The “building blocks” control-function program modules in the SLPC include functions such as basic PID control, sample-and –hold PI control and PID control with batch switch.
• Programming the SLPC-using the SPRG programmer – is as easy as programming a calculator.
• The program is stored in EPROM - so the controller functions can be changed simply by changing the EPROM. Stock keeping is simplified-one SLPC can perform the functions of many different conventional instruments simply by changing the EPROM (program).
• Communications functions allow the SLPC controller to be remotely operated and supervised from a central CRT-display operator console (UPOC) or supervisory computer.
• Abnormal signals from the field are detected; controller self-diagnostic programs are also built in. Communications functions allow the SLPC controller to be remotely operated and supervised from a central CRT-display operator console (UPOC) or supervisory computer.
• Abnormal signals from the field are detected; controller self-diagnostic programs are also built in. Manual backup can be used even if the CPU in the controller has failed.
APPLICATION:
The following application examples illustrate the functional versatility of the SLPC controller.
• Flow control with Temperature-Pressure Compensation.
• Flow Ratio Control.
• Temperature control of furnace.
• Compressor surge protection control.
• Flow-Temperature cascade control loop.
• Combustion control in furnace.
PROGRAMMING PROCEDURE
• Determine number of inputs
• Manipulated output requirements
• BSC, CSC, SSC OK?
• Operation requirement between control elements in CSC?
• CNT=1 O 3?
• Use of A,FL registers
• Check the data to be operated and indicated on the front. Connect the required indicators and controls.
• Determine scaling of computational signal.
• Finalize the number of computational parameters and constants.
• Number of computation units with a device address.
• Roughly check the programming steps.
• Check program steps
• Check for computation overflow
• Key in program using both of SLPC and SPRG.
• Print out program on the printer and file it