Hello, I am currently in the process of translating an OMRON CPM2* PLC program from CX-Programmer to Siemens TIA Portal for compatibility with a new S7-1215 CPU. The program utilizes ladder logic, however, I have encountered a discrepancy with the NO contact instructions in the OMRON program. Despite searching extensively, I have been unable to determine the distinction between the two types of NO contacts present. I have included a screenshot (labeled 'ladder.png') to illustrate the issue: the ladder diagram displays standard NO contacts 'P_On' and 'BWASH_INIT1' on the left side, followed by two additional NO contacts in parallel below - labeled '203.09' and 'MAN_BWASH2' - featuring a double vertical line on the left side of the NO contact symbol instead of a single line. When viewing the rung in statement list format, a different view is presented (refer to 'STL.png' for comparison). I would greatly appreciate any insights or explanations regarding the distinction between these two variations of NO contacts. Thank you.
In Mitsubishi PLCs, the contacts from a DIFU function have a unique arrangement that sets them apart from regular N/O or N/C contacts. Instead of having to call the DIFU or DIFD function, the differentiation is indicated by an up arrow or down arrow inside the contact - a feature not found in other PLCs. This distinction helps to visually identify oneshot contacts. It appears that you are located in Derby, which is only a short distance from my location.
Thank you for the clarification, it all makes sense now. I have been a lifelong resident of Derby, but I find myself working in various locations due to my PLC engineering role at a systems integrator. Wishing you a great weekend and thanks once more.
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The difference between the two indicate program scope in relation to variable access. The single vertical line on your 'P_On' and 'BWASH_INIT1' contacts suggests they're local or instance variables, only accessible within their own program block or instance. As for '203.09' and 'MAN_BWASH2' contacts with a double line, they are typically global variables. These can be accessed from any part of your program. The different views you're seeing in ladder diagram and statement list format likely result from this variable scope distinction. You’ll need to take this into account when doing your programming translation.
From your screenshot, it appears the NO contacts with the double line in your OMRON program are edge trigger instructions; more specifically, the positive edge trigger (or P_trig). In Siemens, these would correspond to the "P" function in ladder logic, or the "POS" function in your STL. These are used to identify the exact moment a transition from off (0) to on (1) occurs. Hence, these instructions would only be true for one PLC scan cycle and then turn false again, making them ideal for triggering specific events. Studying and understanding the original program flow will be crucial to ensuring your state transition processes are preserved during translation.
From your description, it sounds like the NO contacts with the double vertical line might represent instructions––not just the standard ones in Siemens TIA Portal. This double line could denote that these contacts are edge-triggered and are associated with rising or falling edges of signals. If this is the case, they aren't typical of ladder logic, but included as part of the high-level language support more akin to Structured Text or Statement List format. Be sure to review your new S7 CPU instruction list and documentation to see if similar edge-detection instructions are supported. Also, cross-check the instructions associated with '203.09' and 'MAN_BWASH2' in the OMRON program. Your answer might be hidden there!
It sounds like you're tackling quite a challenge with that translation! The distinction you're seeing with the NO contacts could be due to the way OMRON represents normally open contacts under different conditions or states. The double vertical line usually indicates a specific type of internal coil or function, perhaps something like a latch or a specific status indicator. In some cases, it may represent a "virtual" contact that reflects a condition rather than a direct hardware input. I'd recommend checking the OMRON documentation for specifics on the symbols they use, as they often have unique meanings in their context. Good luck with your translation to the Siemens platform!
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Answer: - The standard NO contacts have a single line symbol, while the NO contacts with a double vertical line in OMRON CX-Programmer represent a specific variation that may have a different functionality or purpose.
Answer: - Translating ladder logic programs with different NO contact variations involves understanding the specific logic implemented by each variation and replicating it in the target platform.
Answer: - The specific labels '203.09' and 'MAN_BWASH2' assigned to NO contacts in the ladder diagram may indicate their respective functions or connections within the PLC program. Understanding the context of these labels is essential for interpreting their roles accurately.
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