Mitsubishi PLC substrate has a reserved slot when the module address is determined - Database & Sql Blog Articles

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When working with Mitsubishi PLC systems, up to 8 modules (excluding the CPU) can be installed on a single PCB. As shown in the diagram, when all slots are filled with modules, their addresses can be determined based on the actual I/O points of each module. However, if there are reserved slots between modules, it becomes unclear how many I/O points are allocated for those empty slots—whether it's 32, 64, or 128 points. This uncertainty makes it difficult to assign proper addresses to the modules that come after the reserved slot.

To resolve this issue, you need to manually define the number of I/O points that the reserved slot occupies within the PLC parameters. Here’s how you can do it:

1. Open the Project Manager and double-click on "Parameters" → "PLC Parameters".
2. In the "Parameter Settings" window that appears, navigate to the "I/O Assignment" tab.

Within this tab, you can specify the number of I/O points used by each module installed in the slots. This also includes the reserved slots, as shown in the example for Slot 3 in the diagram. The following options are available:

• Type: Select the type of module installed in the slot. If no module is installed, choose "Empty".
• Type Name: You can add an identifying name for the module if needed.
• Points: Choose the number of I/O points that the module or reserved slot uses.
• Start XY: This allows you to manually set the starting address for the module's I/O data.

By properly configuring these settings, you ensure that the PLC system assigns accurate addresses to all modules, even when some slots are left unused. This helps prevent conflicts and ensures smooth operation of the entire system. Always double-check your configuration before finalizing the project setup.