Debugging and maintenance of EPSON RC90/RC90-B controller

EPSON RC90/RC90-B Controller: Complete Guide to Installation, Debugging, and Troubleshooting

In industrial robot applications, stable operation and fast fault handling of controllers are key to ensuring production efficiency. The EPSON RC90/RC90-B robot controller is designed specifically for LS series SCARA robots, supporting EPSON RC+7.0 software environment, providing 4-axis AC servo control, rich I/O interfaces, and multiple optional communication modules. This article is based on the RC90/RC90-B controller hardware manual, systematically explaining its installation specifications, cable connections, operating modes, development environment configuration, safety circuit wiring, I/O remote signal settings, daily maintenance, and typical troubleshooting methods, providing a practical technical guide for on-site engineers.

Product Overview and Safety Notice

RC90 and RC90-B are EPSON's RC90 series robot controllers, with the main differences being the type of I/O output circuit and some hardware layouts. Both use 32-bit microprocessors to control up to 4 AC servo motors. The standard I/O is 24 point input/16 point output (can be remotely assigned), and Ethernet (100BASE-TX/10BASE-T), RS-232C, and USB interfaces are standard. It supports developing PCs through USB or Ethernet connections.

Core security principles:

The controller contains high-voltage capacitors inside, and after power failure, it must wait for 15 minutes before opening the hood.

The emergency stop switch and safety door input must use dual redundant normally closed contacts and be correctly connected to the EMERGENCE interface.

Before operating the robot at any time, it is necessary to confirm that the safety protection device is effective.

The manual repeatedly emphasizes that only trained and qualified personnel can install, program, and maintain this equipment. Any act of plugging or unplugging cables while the power is on may result in electric shock or equipment damage.

Hardware installation and environmental requirements

2.1 Installation direction and spacing

The RC90/RC90-B controller is designed for cabinet wall hanging or desktop upright installation (see installation diagram). To ensure heat dissipation, it is necessary to:

Reserve a ventilation space of 100mm on the top, bottom, left, and right sides of the controller.

The installation direction must ensure that the air inlet and outlet are unobstructed (air inlet below the front panel, air outlet at the back and above).

Do not install the controller near a heat source or in direct sunlight.

2.2 Environmental conditions

Environmental temperature: 5-40 ℃

Relative humidity: 20% to 80% (without condensation)

Pollution level: 2 (compliant with IEC 61800-5-1)

Altitude: ≤ 1000 meters (downgrading is required for use above 1000 meters)

2.3 Power Requirements

RC90/RC90-B is powered by single-phase 200-240 VAC and has a maximum rated capacity of 2.5 kVA (depending on the connected robotic arm). Specific peak current: about 70 A (2 ms) at the moment of power on, and about 50 A (2 ms) at the moment of motor connection. Leakage circuit breakers or circuit breakers rated at 15A or below must be installed, and it is recommended to use inverter compatible leakage protectors to avoid high-frequency leakage current tripping.

Cable connection and wiring specifications

3.1 Main Interface Description

Interface Function Remarks

The AC IN 200-240 VAC power input terminal must be grounded (green/yellow wire)

M/C POWER Robot Arm Main Power Supply (20 Pin) Special Cable

M/C ignal mechanical arm encoder signal (36 pin) dedicated cable

Emergency stop, safety door, latch release D-sub 25 pin

If the TP port is not connected to the teaching device or bypass plug, the bypass plug must be inserted

USB (development) connected to PC (EPSON RC+7.0) USB 2.0, maximum length 5 m

LAN Ethernet communication (RJ45) 100BASE-TX/10BASE-T

I/O connector standard I/O (24 inputs/16 outputs) D-sub 50 pin

RS-232C standard serial port D-sub 9-pin

Memory port USB memory (for state storage) only supports USB 2.0 flash drives

3.2 Key Wiring Precautions

Power grounding: The green/yellow wire of the power cord must be connected to the factory grounding terminal, with a grounding resistance of ≤ 100 Ω.

Mechanical arm connection check: The front of the controller is labeled with a "connection check label", which must be matched with the corresponding serial number of the mechanical arm. Incorrect connections can lead to abnormal or even dangerous robot movements.

EMERGENCE interface: The 24V output of this interface is only used for emergency stop circuits and cannot be used for other loads. The emergency stop switch must use a dual contact normally closed switch, with two contacts connected to pins (1-2) and (14-15) respectively, and voltage read back at pins (3-4) and (16-17). If two redundant input states are inconsistent for more than 2 seconds, the controller will report a fatal error and lock.

TP port: If the teaching pendant (TP1/TP2) is not used, the accompanying bypass plug must be inserted, otherwise the controller will always be in emergency stop state.

Operation mode and switching

RC90/RC90-B supports three operating modes:

Mode Usage Safety Door Status Motor Power

TEACH teaching point data, can be manually opened by pressing the enable switch for low power

AUTO automatic running program must turn off high power

TEST low-speed program verification, the safety door can be opened or closed, and the low-power switch (T1 mode) needs to be pressed to enable it

Mode switching is achieved through the mode selection key switch of the teaching pendant. When switching from TEACH to AUTO, if the safety door is open and the latch release input is OFF, the controller will maintain the safety lock state. The safety door needs to be closed first, and then the latch release input (pins 18-19) needs to be closed before entering AUTO.

Engineering Tip: When using remote I/O control, the control device must be set to "remote" and the "AutoMode" output must be confirmed to be ON for remote input to be effective.

Develop PC connectivity and software settings

5.1 USB connection

EPSON RC+7.0 (recommended Ver. 7.0.2 or higher) must be installed first before connecting the USB cable to the controller and PC. If the order is reversed, Windows will pop up the "Add New Hardware Wizard", and you should click "Cancel".

Go to [Setup] → [PC to Controller Communications] in RC+, select "No.1 USB", and click Connect. After successful connection, the status will display "Connected".

When disconnecting, you should first click Disconnect in the software, and then unplug the USB cable, otherwise the robot will stop urgently.

5.2 Ethernet Connection

The factory IP address of the controller is 192.168.0.1, and the subnet mask is 255.255.255.0. The IP can be modified through [Setup] → [Controller] → [Configuration] of RC+. Note: from the firmware version Ver.7.4.8. x, if you use the global IP address to access the Internet, you must perform password authentication. For safety reasons, it is recommended to limit the use of the controller to the local area network (private IP address range).

5.3 Controller state storage function

The front panel of the controller has a USB memory port and a trigger button. Insert a compatible USB flash drive, wait for about 10 seconds for recognition, press the trigger button, and the controller will automatically package and save project files, robot parameters, I/O status, error history, etc. to the USB drive. When saved successfully, the TEACH, AUTO, and PROGRAMM LEDs will light up simultaneously for 2 seconds. This feature can be used for quick backup and remote support.

Emergency stop and safety circuit design

The EMERGENCE interface (D-sub 25 pin) is the core of security design. The key signals are as follows:

Pin signal description

1-2 ESW11, ESW12 emergency stop switch contact 1 (normally closed)

14-15 ESW21, ESW22 emergency stop switch contact 2 (normally closed)

3-4 ESTOP1+, ESTOP1- Emergency Stop Circuit 1 Input

16-17 ESTOP2+, ESTOP2- Emergency Stop Circuit 2 Input

7-8 SD11, SD12 safety door input 1

20-21 SD21, SD22 Safety Gate Input 2

18-19 SDLATCH1, SDLATCH2 latch release input

9, 10, 22, 23 24V output provides power for external emergency stop button

11,12,24,25 24VGND public area

Wiring points:

The emergency stop switch must be of the double pole double throw (DPST) normally closed type, with each pair of contacts connected to a redundant circuit.

The safety door switch also requires two sets of independent normally closed contacts.

The latch release input is used to release the latch state of the safety door open or TEACH mode. During normal operation, this input should be closed (ON).

All external emergency stop buttons should be connected in series in the ESTOP1/2 circuit, with a total circuit resistance of ≤ 1 Ω.

When the emergency stop is pressed, the motor power is immediately cut off, the dynamic brake short circuits the motor winding, and the robotic arm quickly stops. When restoring, you need to release the button first and then send the Reset command (which can be done through remote input or RC+menu).

I/O configuration and remote control signals

7.1 Standard I/O Electrical Characteristics (RC90 vs RC90-B)

The output of RC90 is a transistor type, which is fixed as a drain or source type when shipped and cannot be changed on-site. The rated output current is 100 mA/point, with a maximum of 30V. It is important to note that reversing the polarity may damage the circuit.

The output of RC90-B adopts a non-polar PhotoMOS relay with an average on resistance of 0.13 Ω, which can withstand loads up to 5A (resistive)/2A (inductive). Input voltage range 12-24V, ON voltage ≥ 10.8V, OFF voltage ≤ 5V, input current 3mA @ 24V.

7.2 Remote Input/Output Function Allocation

The initial state of the controller predefines 8 inputs (0-7) and 8 outputs (0-7) as remote functions, mapped as follows:

Input function and output function

0 Start 0 Ready

1 SelProg1 1 Running

2 SelProg2 2 Paused

3 SelProg4 3 Error

4 Stop 4 EstopOn

5 Pause 5 SafeguardOn

6 Continue 6 SError

7 Reset 7 Warning

Users can reassign these functions to different I/O points through RC+'s [Setup] → [System Configuration] → [Remote Control], or allocate functions to extended I/O or fieldbus modules.

Key timing sequence:

The pulse width of the remote input signal must be ≥ 25 ms to be reliably detected.

Effective from Start input to MotorsOn output, with a typical delay of approximately 40 ms.

After the emergency stop is triggered, the EStopOn output immediately turns on and the motor power is cut off.

Option board expansion

RC90/RC90-B provides two option slots for installing the following cards:

Expansion I/O board: Each board adds 24 inputs/16 outputs (similar to standard I/O, sink/source type needs to be selected).

Fieldbus board: Supports DeviceNet, PROFIBUS-DP, CC Link, PROFINET, EtherNet/IP, EtherCAT for high-speed data exchange with PLCs.

RS-232C board: Provides two additional RS-232C ports (up to 4 expansion serial ports).

Analog I/O board: Optional 1 channel (DAC only) or 4 channels (2 in/2 out), 16 bit resolution, configurable voltage/current.

EUROMOP67 board: a standard interface designed for injection molding machines and robots, including 15 inputs/16 outputs and emergency stop safety relays.

When installing the option board, it is necessary to remove the top cover, fix the board, and set the DIP switch as needed (such as setting SW1 to the corresponding position for EUROMOP67 board). The slots are counted as slot 1 and slot 2 from the left side of the front of the controller.

9、 Maintenance and Parts Replacement

9.1 Regular inspection cycle

Component maintenance operation cycle

Fan filter cleaning or replacement>once a month

Fan replacement (abnormal noise or error 515) for approximately 30000 hours

Battery replacement (error 511 or 9011) every 5 years

CF card replacement (damaged or firmware upgrade failure) as needed

9.2 Battery replacement steps

The controller motherboard battery (model 2113554) is used to save project files, parameters, and globally retained variables. When replacing:

Backup controller data (via RC+or USB state storage).

Turn off the controller power and unplug the power plug.

Remove the top cover (6 or 10 screws).

Disconnect the battery connector and remove the old battery.

Install the new battery within 10 minutes and ensure that the fixing buckle is in place.

Reinstall the top cover, power on, and clear the battery alarm (reset through RC+'s [Tools] → [Controller] → [Maintenance]).

Attention: It is recommended to power on the controller for at least 1 minute before replacement to charge the internal capacitor, which can extend the memory retention time.

9.3 Fan and Filter Cleaning

The fan filter is located under the front panel, and the filter can be removed by removing two screws. Use a vacuum cleaner to clean, and replace if the blockage is severe (part number 2195107 white or 1520975 black). Clean and reinstall to ensure good ventilation.

9.4 Firmware Upgrade and Recovery

When the controller fails to start or has abnormal functions, a dedicated firmware CD ROM can be used for upgrading or initialization:

Connect the PC to the controller using a USB cable (Ethernet upgrade not supported).

Execute Ctrlsetup70.exe and select Upgrade or Initialize.

Follow the prompts to complete the firmware transfer (approximately a few minutes), during which do not power off or unplug the USB.

After initialization, the previously backed up data recovery project needs to be used.

Starting from firmware Ver.7.4.8. x, if the controller IP is set to the global address, an additional security confirmation dialog box will pop up during the upgrade. The user can check "Disable connection password" to disable password authentication (not recommended for use in the Internet environment).

Common faults and error code troubleshooting

When the controller malfunctions, the front panel LED will indicate the error type:

Meaning of LED status

ERROR constantly on fatal error (system stopped)

ERROR flashing non fatal error (warning)

E-STOP constantly on emergency stop status

TEACH/AUTO/PROGRAMME is flashing and running normally

The following are high-frequency faults and solutions:

10.1 Error 511 (low battery voltage)

Phenomenon: ERROR flashes and the system prompts "Battery voltage of the CPU board backup is lower than the allowed voltage".

Solution: Immediately replace the CPU board battery (refer to 9.2), and keep the controller powered on before replacement.

10.2 Error 515/516 (low fan speed)

Phenomenon: The internal temperature of the controller rises, which may trigger an overheating alarm.

Solution: Clean the fan filter. If it is ineffective, replace the fan (part number 2157260).

10.3 Unable to connect to PC via USB

Phenomenon: RC+reports "Connection failure (1805)".

handle:

Confirm that EPSON RC+7.0 has been installed and version ≥ 7.0.2.

Open Windows Device Manager and check if there is "EPSON Robot Controller RC170" under "Universal Serial Bus Controller". If it appears in "Other Devices", please uninstall and re plug the USB.

Replace the USB cable with a length not exceeding 5 meters and avoid using a USB hub.

10.4 Emergency stop cannot be lifted

Phenomenon: The E-STOP LED is constantly on, and the Remote reset is ineffective.

handle:

Check if pins 1-2 and 14-15 of the EMERGENCE interface are conductive (should be 0 Ω after emergency stop release).

Check the voltage of pins 3-4 and 16-17 (+24V should be normal for 24V).

If the TP port is not connected to the teaching pendant, confirm that the bypass plug has been inserted.

If an external safety relay is used, check its output contact status.

10.5 Remote I/O not responding

Phenomenon: After the Start signal is input, the robot does not move and the Ready output is normal.

handle:

Check if the control device is set to "Remote" (System Configuration → Controller → Control Device in RC+).

Check if the AutoMode output is ON (if OFF, it means the controller is not in remote ready state).

Confirm the input status of the safety gate (SafeguardOn output should be OFF to operate).

10.6 Encoder battery alarm (error 401/9018)

Phenomenon: After the robot is powered on, it requires resetting the encoder.

handle:

Replace the battery of the robotic arm body (non controller battery).

Execute the ENC-RET command to reset the multi cycle data, and then recalibrate the origin.