A Safety PLC is intended to reliably accomplish safety-related operations in order to protect people, machinery, & the environment. Unlike regular PLCs, Safety PLCs are designed to meet high safety standards (such as IEC 61508 & IEC 61511) & can carry out safety programs in the case of failure.
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Consider about the necessary safety integrity level (SIL). SIL levels are ranked from 1 to 3, where SIL3 is the maximum level of safety. Select a PLC that fulfills the necessary SIL requirements, or surpasses them.
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Verify if the PLC has received functional safety certification from safety standards bodies like TÜV or UL. By doing this, the hardware & software are ensured to meet safety standards.
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Analyze the environment that programs in. Select a PLC with programming software that facilitates the creation and validation of safety routines. See if there are any integrated diagnostics.
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Evaluate the possibilities for redundancy. To lessen the probability of hardware failures, many safety PLCs provide redundancy features. Replicated power supply, CPUs, I/O modules, & network connections are among the options that are accessible.
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Analyze the tests and diagnostics. A safety PLC needs to have strong self-diagnostics and testing capabilities. This covers functions like fault monitoring, watchdog clocks, and cross-channel checks.
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Take consideration for failsafe actions. If a failure is found, the PLC ought to enter a known safe state. For example, certain outputs can be retained in the last state or deactivated.
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Examine the I/O capabilities. Verify that the PLC has enough input & output capacity for the number of devices and scale of your application. One option is to use safety I/O modules.
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Assess the level of integration flexibility. Examine the PLC’s ease of integration with both conventional control systems and safety features. Is it capable of transmitting safety information to non-safety devices
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Analyze your alternatives for training and assistance. When establishing & maintaining a safety PLC system, good supplier support and training materials are essential.
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Simplify safety programming by properly organizing blocks, utilizing certified blocks, & selecting diagnostic measures. Avoid maintaining or bypassing branches. Choose for “zero-oriented” features such as RS flip-flops. Keep the code simple and easy to understand.