Our technical support team regularly handles a wide range of queries across motion control, PLCs, and industrial networking. Below are six of the most common issues we see, along with guidance to help you diagnose and resolve them quickly.
Motion Control
1. Low-Voltage Servo Control: Have You Wired Your Load Voltage?
A frequent misconception is that the logic 24 V supply and the load supply are internally linked. They are not. Most low-voltage motion systems operate in the 24–48 VDC range, and the drive keeps the load voltage isolated from the logic voltage.
Because of this separation, it’s common to forget to wire the load voltage—especially on Festo stepper solutions—resulting in load undervoltage faults.
Tip: Always verify that the dedicated load voltage input is wired and correctly supplied before commissioning.
2. G120 Drives: Remember to End Safety Commissioning
On the Siemens G120 platform, beginning safety commissioning without properly ending it will prevent the drive from running. This also complicates the acceptance testing process.
Recommended procedure:
Start safety commissioning.
Complete all required safety settings.
End safety commissioning.
Save the configuration to the EPROM.
Complete the acceptance test—ideally using the wizard in StartDrive Advanced, which automatically generates the E-Stop performance record and safety documentation.
CPUs, PLCs, and TIA Portal
3. TIA Portal Connection Issues
Connectivity problems in TIA Portal can stem from several configuration or firmware mismatches.
Troubleshooting checklist:
Firmware alignment: Confirm the device firmware matches the version selected in the TIA Portal project. Upgrade if needed.
Date and time validation: Security certificates rely on valid time ranges. Incorrect system dates can cause communication failure.
A workaround is to perform a time check on startup, set the CPU’s date/time within the certificate validity period, and sync other devices using the CPU as an NTP server.IP addressing: Verify IP settings and ensure physical cabling and network topology are correct.
4. Migrating from Legacy Systems (S7-300 → S7-1500)
With S7-300 PLCs being phased out, many users are moving from STEP 7 Classic to TIA Portal with S7-1500 hardware. Successful migration requires preparation.
Key recommendations:
Review original documentation: Understanding how I/O cards and features were used in the STEP 7 program will guide your selection of the appropriate CPU and I/O in the new platform.
Use the migration guide: Siemens provides official migration tools, but both STEP 7 and TIA Portal must be installed to carry out the conversion.
If the original project file is missing:
You can upload the program from the CPU, but be aware that comments and symbols will not be included, resulting in significant reverse engineering unless you know the system well.
Industrial Networking
5. Ewon VPN Connectivity / Talk2M Setup Problems
A common issue in Ewon installations is incorrect or incomplete WAN configuration during setup. Users often assume the device will auto-detect the right interface—Ethernet, Wi-Fi, or cellular—but this isn’t guaranteed.
If the WAN interface is misconfigured (e.g., DHCP on a static network, wrong interface selected), the device cannot reach the Talk2M servers, leading to errors such as “VPN Tunnelling Error” or “Cannot Reach Server.”
Troubleshooting checklist:
Run the Internet Wizard again and confirm the correct WAN interface.
Verify IP settings, especially the default gateway.
Use the Talk2M Connection Checker to ensure required outbound ports are open.
6. Scalance S / SC Firewalls: Missing NAT or Incorrect Rule Order
When configuring Scalance firewalls, users often create the right rules but overlook the importance of rule order. Scalance devices process rules top-down, so a broad “deny” rule above a specific “allow” rule will still block traffic.
This often results in “Device unreachable” or inability to access PLCs or HMIs over VPN.
Troubleshooting checklist:
Verify rule order: place specific allow rules above general deny rules.
Confirm NAT is enabled when routing between different subnets (if required by the application).
Ensure both inbound and outbound directions are properly configured.
About Technical Support at Parmley Graham
At Parmley Graham we bridge the gap between complex technologies and your unique manufacturing challenges. We are a trusted partner of world leading manufacturers due to our commitment to quality and technical expertise.
To discuss your next project or for queries about your existing operations contact our team today at support@parmley-graham.co.uk or 0191 478 0404.