TelePACE™ Ladder Logic Editor Functions & Applications

Custom Ladder Logic Functions

The application combines the simplicity of traditional ladder logic with the flexibility and power of custom functions. Users familiar with ladder logic programming techniques and elements such as contacts, coils and timers can easily progress to the more advanced SCADA functions that are available with SP series controllers. These functions include:

• DIAL, INIM: Control dial-up phone line communication
• DLOG, GETL: Create datalog and retrieve logged data
• FLOW: Accumulate and log flow totals based on pulse-type input
• TOTL: Totalize and log values based on rate input
• HART: Send a HART protocol command and process the response
• MSTR: Send a serial protocol message
• MSIP: Send a TCP/IP protocol message
• PIDA, PIDD: Perform an analog or digital output-based PID algorithm
• SCAL: Scale an integer to a floating-point value
• SUBR: Define subroutines

Online Functionality

TelePACE software provides a facility for remote or local online editing and monitoring of ladder logic programs. Minor changes to the ladder logic code can be made online. This ensures that only the new code is written to the controller and not the entire application.

Program execution can be monitored in real time with logic power-flow being displayed on the logic network itself. Input/output (I/O) database variable values are conveniently displayed on the register editor dialog where custom lists of variables are easily created.

Process variables, controlled by the ladder logic code, can be forced to predetermined values. This is handy when debugging code in the absence of actual input process values or when temporarily removing a process input from service for maintenance purposes.

Offline Development

Ladder logic code is easily and quickly developed using the built-in editing features of the program. These include the cutting and pasting of code fragments or entire networks, special configuration dialogs for complex function blocks and the use of subroutines to compartmentalize sections of code.

Important logic documentation can be appended to the network where the logic resides, making the code more understandable for future users. Tag names, assigned to individual I/O database points, can further enhance understandability.

Concurrent C/C++ Code Execution

For additional programming power, a TelePACE application can execute in a SP series controller concurrently with C/C++ code. Process data generated in either application can be passed to the other through the common I/O database. This means, for example, that the results of complex mathematical algorithms, implemented using C/C++, can be used by the application to control the process.

In a typical oil and gas application, Weatherford’s SS 4203 gas flow computer C/C++ code handles the gas flow calculation and logging functions while a concurrently-executing TelePACE application handles the remainder of the well site automation and communication duties; which could include the control of equipment such as pumps and motor starters.