How to troubleshoot Allen Bradley SLC 500 Serial Connection to Flexy

APPLICABLE PRODUCTS

Flexy with built-in serial port

Flexy with FLA 3301 serial extension card

1. Verify serial port configuration

• Ensure your Flexy's IO Port is set correctly to your serial device's settings and are using the correct COM Port.  This is located in Setup -> System -> Communication -> General -> Serial Ports -> IO Port.  Your COM # is dependent on which serial port you are using for your connection to the Flexy.
• On the FLA 3301 serial extension card, port S2 only supports RS-232, while port S1 is configurable to RS-232 or RS-485. This change requires a technician to remove the extension card and change the state of a group of DIP switches on the card as explained in the FLA 3301 serial extension card installation guide.

2. Verify DF1 IO Server configuration

• Ensure the DF1 IO Server configuration matches the PLC serial communication parameters, including:

  • Baud rate
  • Data bits
  • Parity
  • Stop bits
  • Error-checking method (CRC/BCC)
  • PLC node address

  Also verify that Bridge EIP Connection is enabled.

• Make sure Topic is properly setup and enabled.  Please refer to our Allen-Bradley serial polling setup guide for more details.

3. Verify physical serial connection and wiring

• Verify that the correct cable is being used between the Flexy and the SLC 500. 
• Confirm the PLC's serial port is configured for DF1 communication. 
• Check for loose connections or damaged cabling. Verify that RS-232 and RS-485 wiring standards are not being mixed. 
• If using the FLA 3301, confirm the DIP switch settings match the desired electrical interface.
• Test the serial cable, to ensure a proper connect can be made, such as using a laptop use a serial port.

4. Verify communication using a test tag

• Create a test tag that references a known valid SLC 500 memory address. If the tag updates successfully, communication between the Flexy and PLC has been established.

5. Verify Ethernet/IP port configuration

• In firmware version 15, the Ethernet/IP Port is closed by default.  In order to connect to the SLC 500 Series, you must re-enable this port, using its default (44818) or whichever port you will be communicating on.  This is adjusted in Tags > IO Servers > General > Global Settings.  Make sure to reboot to apply changes.

6. Verify remote access software configuration

• For the SLC 500 series, you will need to use the "AB_ETH-1, Ethernet" driver.
• Please refer to our Allen-Bradley serial remote connection guide for proper setup.

7. Verify Ewon and PLC gateway settings

• If your Flexy's NAT settings are set to "NAT on LAN (Plug'n Route)", the Flexy automatically performs network address translation (NAT) and acts as the gateway for PLC communications.   
• However, if "NAT on LAN (Plug'n Route)" is not enabled, you must set the gateway of your PLC to the Flexy's LAN IP.  This setting is accessible under Setup -> System -> Communication -> Networking -> Routing -> NAT -> Apply NAT to connection.
  
  

8. Address slow or unstable connections

• Rockwell software can be sensitive to latency during remote programming sessions. If remote access is unstable or frequently disconnects, configure the VPN connection to use TCP instead of UDP. TCP is generally more tolerant of high-latency or unreliable network conditions.  To force TCP, you must re-run the VPN wizard locally on the Flexy, use the correct activation key linked to your Ewon device via Ecatcher, and in advanced parameters select View -> Force to TCP -> Complete wizard.

  

9. Verify connectivity

• We have seen in the past where a device will look like it is unreachable in PLC software such as RSLinx or Studio 5000, yet when trying to connect to the device, the connection is able to be established.  Verify if there is an error when trying to connect or if a connection can be established.

If all of these troubleshooting steps fail, please open up a ticket with our HMS Support team, provide an up to date back up from the Ewon, what relevant testing has been done, and any errors you may be receiving.

ADDITIONAL INFO 

For further troubleshooting a serial connection, please see: Troubleshooting an Ewon Flexy's serial connection – HMS Support Portal

For our guide in Polling Allen Bradley PLCs via Serial Connection: aug-0045-00-en-poll-data-from-allen-bradley-plc-using-serial-protocol.pdf

For our guide in setting up Remote Connection to Allen Bradley PLCs: aug-0035-00-en-configure-remote-access-for-allen-bradley-plc.pdf 

FLA 3301 Installation Guide: Ewon Flexy Extension Card FLA 3301 - 2 Serial Ports extension card - 2 Serial Ports

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