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TRiLOGI - The Most User-Friendly Ladder Logic Editor,
Compiler and Real-time Ladder Logic Simulator

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Although H-Series PLC may look like an ordinary single-board computer, they are all programmable using the "Relay-Ladder Logic" language which is the most popular programming language used by all major manufacturer of PLCs such as Allan-Bradley, Siemens AG and OMRON, etc. Although programs written in Relay Ladder Logic cannot directly manipulate the microcontroller's internal hardware as easily as the assembly language, such programs are however much easier to write and are generally understood by all electricians around the world who need not have any knowledge about microcontrollers at all.

Fig 1 - TRiLOGI Editor Screen

Thanks to our extremely powerful yet very user-friendly Relay ladder logic editor-cum-simulator software - TRiLOGI, programming H-series PLC become an almost trivial task. TRiLOGI runs on any IBMPC compatible computer and provides complete pull-down menus, pop-up windows and on-line context-sensitive help systems. As you may observe from the above screen, you can see that all I/Os may be defined using very meaningful names such as Start, Stop, etc. in the program and the relationship between each I/Os are defined by how the imaginary "current" could flow through the circuit connection.

The following sections describe the main features of TRiLOGI including the types of functions it supports.

1. Insert Element Menu

Fig 2- Intuitive pull-down "Ins Element" Menu

To add an element to the ladder diagram, you simply press the <Ins> key and pick an item from the Insert Element pull down menu as shown above. This menu lets you create Normally-Open (NO) or Normally-Closed (NC) contacts in series or in parallel. One or more coils can be connected by choosing Item "7" or "8". To insert a special function, select Item "9" or "0" (for multiple function) and the special function menu will appear as described in the next section.

2. Special Function Menu

Fig 3 - Special Functions Menu

  1. Reversible Counter Function: [DNctr], [Upctr] and [Rsctr] - The [DNctr], [UPctr] and [RSctr] functions work together to implement reversible counter functions on any of the 128 counters supported by TRiLOGI. Unlike the ordinary down-counter, a reversible counter is a circular counter which changes the counter present value (PV) between 0 and the set-value (SV). When you try to increment the counter pass the "Set Value", it will overflow to become '0'. Likewise if you try to decrement the counter beyond '0', it will underflow to become the "Set Value". All three counter functions [DNctr], [UPctr] and [RSctr] can operate on any built-in counters.
  2. [AVseq],[RSseq] and [StepN] -These 3 functions control any one of the 8 sequencers supported by TRiLOGI. A sequencer is very useful for programming machines or processes which operate in fixed sequences. These machines operate in fixed, clearly distinguishable step-by-step order, starting from an initial step and progressing to the final step and then restart from the initial step again. [Avseq] advances the step counter, [Rsseq] clears the counter to inactive and [StepN] function allows you to set the step counter of the sequencer to any integer value between 0 and 31. [RSctr] - This function resets the counter to inactive state.
  3. [Latch],[Clear] - When activated, the associated output or internal relay will remain ON until it is reset by the [Clear] function acted on the same output or relay.

[Ilock],[ILoff] - This is equivalent to a master relay with sub-branches as illustrated below:

Figure 4: [ILock] function & its Equivalence

  1. [DIFU]-The associated relay will turn on for one scan time when its execution condition goes from OFF to ON.
  2. [DIFD]-The associated relay will turn on for one scan time when its execution condition goes from ON to OFF.
  3. [MaRST] - An ON condition to this function clears all mailbox inputs, outputs, relays timers and counter bits to OFF, resets all timers counters/sequencers to inactive state, and clears all latched relay bits.

3. Special Bits Menu

Fig 5- Special Bits Menu

  1. Clock Pulse - Six clock pulses with period of 0.01s to 1.0 minute are available on the H-series PLC. They can be used as a NO or NC contact in the ladder diagram.
  2. Normally On Flag - If for some reason you require a permanently ON or OFF condition this flag can be used to advantage.
  3. First Scan Pulse - This flag with be turned ON for one scan time when the PLC is first powered ON or when host computer issue a Reset command.
  4. Sequencer 1~8 - H-series PLC supports 8 sequencers, and each step of any one of the sequencer can be used as a contact in the ladder diagram. E.g. Seq2:5 represents Step #5 of sequencer #2 , which means that the contact with the name "Seq2:5" will be turned ON when the step counter of the sequencer #2 reaches the value of '5' and will be OFF when the step counter is at any other value. Each sequencer supports up to 32 steps (Step #0 to Step #31).

4. Real Time Simulation

Fig 6 - Real Time Simulator Screen

While constructing your ladder program you can simulate it using TRiLOGI's unique real-time Simulator. When you invoke the Simulator, you will see a full screen of I/Os organized into 7 columns:

The first two columns show Inputs, followed by Timers, Counters/Sequencer, Internal Relays and Outputs. Beside each I/O, an indicator lamp indicates whether the I/O is ON or OFF. You can move the highlight bar to any I/O and press the <Enter> key to toggle its status and the status of all the other I/Os will be immediately updated according to the ladder program. A red "*" symbol means an I/O is ON whereas a grey "." means it is OFF.

5. On-Line Monitoring and Control

TRiLOGI can monitor the status of all the I/Os, Timers and Counters of the PLC via its RS232C port. It also permits you to pause the PLC and remotely forced-set or reset any I/Os or even modify the current value of the internal Timers and Counters. The I/O status can either be monitored on a full screen display similar to the Simulator-screen, or directly on the ladder diagram. This feature helps greatly during debugging and fine-tuning of your ladder program.

6. Use of Meaningful Label Names

In TRiLOGI all the I/Os must be defined with unique label names prior to using them to construct the ladder program. Up to 8 characters of alpha-numeric names can be defined which means you can create ladder diagram using far more meaningful names such as "Start" and "Fire" instead of 001, 205 etc. Once defined, the I/O names will be used throughout the entire session of program creation, simulation and monitoring. Any experienced programmer would be know that a program with meaningful names is far easier to create, debug and maintain than one made up of numbers only. Coupled with the powerful Simulator, you have to try it to believe how easy it is to develop your control program using TRiLOGI !

7. Password to Protect Intellectual Property

TRiLOGI allows you to set password protection on the target PLC to prevent unauthorized uploading of your ladder program.

Copyright 2001 Triangle Research International, Inc.
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