Omron C500 PLC Installation and Maintenance Guide

When driving loads with high surge currents such as incandescent lamps, the surge current can reach 10 times the rated current, and a current limiting circuit (such as connecting a resistor in series at the output end or using a buffer circuit) needs to be added

Bidirectional thyristor output (OA series):

Switching voltage: up to 250V AC

Leakage current: 3~6mA, may cause slight illumination of extremely small loads (such as LED lights), and parallel discharge resistors are required

Response time: 1ms (ON), turn off time is 1/2 cycle of the load frequency

Each unit is equipped with two built-in fuses (5A 250V), which can be replaced

5.4 Wiring Separation Principle

I/O signal lines are strictly prohibited from being laid in the same cable tray as high-voltage power lines (>400V 10A or>220V 20A). If parallel wiring is necessary, the spacing should be ≥ 300mm, and a metal partition with intermediate grounding should be used.

The use of shielded twisted pair cables (AWG14) can effectively reduce noise.

It is recommended that the length of the I/O cable should not exceed 10m (special units have separate regulations).

The expansion I/O connection cable (flat cable between CPU rack and expansion rack) must not be in the same slot as the power line.

Expansion cable length: Choose a model that is 20cm longer than the actual distance between the two racks. Standard lengths include 30cm, 50cm, 80cm, 1m, and 2m. The maximum length of a single piece is 2m.

Expand configuration rules

C500 can connect up to 3 expansion I/O racks. The configuration steps are as follows:

CPU rack: Install power supply, CPU unit, and I/O control unit (leftmost I/O slot).

Expansion rack 1: Install the power supply and I/O interface unit (leftmost I/O slot), and then install the I/O unit as needed.

Expansion racks 2 and 3 also require their own power supply and I/O interface units.

Connect the I/O control unit to the first I/O interface unit using an I/O connection cable, and then connect the first interface unit to the second interface unit in series.

Limitations:

The total number of I/O points for all racks shall not exceed 512 points.

Special units, link units, remote I/O master stations, etc. can be installed in CPU racks or expansion racks, but it should be noted that some units can only be installed in specific slots (such as Host Link units that can only be installed in the link slots of the CPU rack or directly on the CPU).

The maximum number of PC Link units is 2, and they can only be installed in the rightmost slots of the CPU rack (different backplane regulations apply).

SYSMAC NET Link unit and Host Link unit cannot be installed simultaneously.

Memory package installation and battery maintenance

7.1 Memory Package Types

The C500 CPU does not have a built-in program storage area and must insert a memory pack.

RAM package: Models 3G2A5-MR431 (16K words), 3G2A5-MR831 (24K words). The data is held by the battery on the CPU backplane (power-off hold). Can read and write online, suitable for debugging stage.

ROM package: Model 3G2A5-MP831 (maximum 24K characters). EPROM chips (2764/27128, etc.) are required to write the program into the chip and insert it. Data is not lost during power outages, but cannot be modified online.

7.2 EPROM chip installation

There are three IC sockets (CHIP0, CHIP1, CHIP2) on the ROM package. Set the jumper according to the required capacity and insert the corresponding chip:

Memory Capacity Jumper Setting CHIP0 CHIP1 CHIP2

8K bytes 128 2764--

16K bytes 128 2764 2764-

24K bytes 128 2764 2764 2764

16K bytes (27128) 128 27128--

24K bytes (27128+2764) 128 27128 2764-

7.3 Memory Package Installation Steps

Power outage: It must be operated with the PLC power turned off.

Use a screwdriver to pry open the memory pack cover on the left side of the CPU front panel (press the buckle inward and push it upwards).

Insert the memory pack (with the component facing left) into the slot and push it evenly to the bottom (there may be slight resistance, indicating that the connector is engaged).

Cover the lid back.

7.4 Battery replacement

The RAM package relies on the internal lithium battery of the CPU to maintain data. When the battery voltage is too low, the ALARM indicator light on the front panel of the CPU flashes and the programmer screen displays "BATT LOW". At this point, the battery should be replaced within a week, otherwise the data will be lost.

Battery model: 3G2A9-BAT08 (lithium battery)

Replacement steps (must be completed within 5 minutes):

If the PLC has been powered off, power on for at least 1 minute and then turn off the power.

Open the battery compartment cover (usually located in the upper right or front of the CPU).

Unplug the old battery connector and immediately insert the new battery.

Cover the compartment lid.

After powering on again, if "BATT LOW" still appears, press the CLR, FUN, MONTR keys on the programmer or power on again to clear the message.

Battery life: Approximately 4 years in a 25 ℃ environment. The higher the temperature, the shorter the lifespan.

Grounding and noise prevention

8.1 Grounding Requirements

Use AWG14 (≥ 2mm ²) copper wire with a grounding resistance of<100 Ω.