MELSEC iQ-R Serial Communication Module User's Manual (Startup) - RJ71C24 - Safety Precautions

Oct 22, 2026

Uploaded by Putri

Manual text provides safety precautions for using the MELSEC iQ-R Serial Communication Module RJ71C24 variants (RJ71C24-R2, RJ71C24-R4). It classifies risks into WARNING and CAUTION and instructs users to implement external safety circuits, emergency stop and protective interlocks, and fail-safe mechanisms so the system operates safely even during faults, watchdog or self-diagnostic errors, abnormal CPU conditions, or communication failures. It also warns against improper signal/data usage and improper power sequencing, and emphasizes safe operation before modifying running controller programs, especially with Safety CPU modes.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages70

Reading Time2 h 56 min

AccessFree to download

Safety precautions

WARNING

CAUTION

Design precautions

MELSEC iQ-R Serial Communication Module User's Manual (Startup) -RJ71C24 -RJ71C24-R2 -RJ71C24-R4 (Read these precautions before using this product. ) Before using this product, please read this manual and the relevant manuals carefully, and pay full attention to safety to handle the product correctly. The precautions given in this manual are concerned with this product only. For the safety precautions for the programmable controller system, refer to the user's manual for the module used and the MELSEC iQ-R Module Configuration Manual. In this manual, the safety precautions are classified into two levels: " WARNING" and " CAUTION". | WARNING | Indicates that incorrect handling may cause hazardous conditions, resulting in death or severe injury. | | --- | --- | | CAUTION | Indicates that incorrect handling may cause hazardous conditions, resulting in minor or moderate injury or property damage. | | --- | --- | | Under some circumstances, failure to observe the precautions given under " CAUTION" may lead to serious | | consequences. Observe the precautions of both levels because they are important for personal and system safety. Make sure that the end users read this manual and then keep the manual in a safe place for future reference. 1 WARNING ● Configure safety circuits external to the programmable controller to ensure that the entire system operates safely even when a fault occurs in the external power supply or the programmable controller. Failure to do so may result in an accident due to an incorrect output or malfunction. (1) Emergency stop circuits, protection circuits, and protective interlock circuits for conflicting operations (such as forward/reverse rotations or upper/lower limit positioning) must be configured external to the programmable controller. (2) When the programmable controller detects an abnormal condition, it stops the operation and all outputs are: • Turned off if the overcurrent or overvoltage protection of the power supply module is activated. • Held or turned off according to the parameter setting if the self-diagnostic function of the CPU module detects an error such as a watchdog timer error. (3) All outputs may be turned on if an error occurs in a part, such as an I/O control part, where the CPU module cannot detect any error. To ensure safety operation in such a case, provide a safety mechanism or a fail-safe circuit external to the programmable controller. For a fail-safe circuit example, refer to the MELSEC iQ-R Module Configuration Manual. (4) Outputs may remain on or off due to a failure of a component such as a relay and transistor in an output circuit. Configure an external circuit for monitoring output signals that could cause a serious accident. ● In an output circuit, when a load current exceeding the rated current or an overcurrent caused by a load short-circuit flows for a long time, it may cause smoke and fire. To prevent this, configure an external safety circuit, such as a fuse. ● Configure a circuit so that the programmable controller is turned on first and then the external power supply. If the external power supply is turned on first, an accident may occur due to an incorrect output or malfunction. ● Configure a circuit so that the external power supply is turned off first and then the programmable controller. If the programmable controller is turned off first, an accident may occur due to an incorrect output or malfunction. ● For the operating status of each station after a communication failure, refer to manuals for the network used. For the manuals, please consult your local Mitsubishi representative. Incorrect output or malfunction due to a communication failure may result in an accident. ● When connecting an external device with a CPU module or intelligent function module to modify data of a running programmable controller, configure an interlock circuit in the program to ensure that the entire system will always operate s

FAQs

What is the difference between WARNING and CAUTION in this manual?

WARNING indicates incorrect handling may cause hazardous conditions resulting in death or severe injury. CAUTION indicates incorrect handling may cause hazardous conditions resulting in minor/moderate injury or property damage.

Why must safety circuits be configured externally to the programmable controller?

External circuits ensure the entire system operates safely even when a fault occurs in external power supply or the programmable controller, preventing accidents from incorrect outputs or malfunctions.

What precautions are required when communication fails?

For station operating status after communication failure, refer to the network manuals, and configure an interlock circuit so the system operates safely even if communications fail. Incorrect output or malfunction may result in an accident.

Oct 22, 2026

Uploaded by Putri