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The device does not turn on or resets

When power is supplied, the PWR LED does not light

Possible cause Solution
Power supply not connected or switched offCheck the power supply. Check if input voltage 24 Vdc is present on terminals
The problem is with power cable, terminals or polarity Check power cable, contact and polarity
Possible cause Solution
No SD card or it's inserted wrong Insert (correctly) SD - card.
“lock”-switch on the SD card is set into Write protect Disable write protection for SD-card
SD - card is damaged Check the SD card on the another device

The device does not boot up, SD card is Ok

Possible cause Solution
WebHMI failure Send the device to the service.

The device reboots

Possible cause Solution
If 3G modem used, network watchdog reboot is selected in Monitoring modem menu (network setup) Disable “reboot” checkbox in Modem monitoring properties
If VPN monitoring option is on and reboot is selected in VPN Monitoring menu (network setup) Disable “reboot” checkbox in VPN monitoring properties
Bad contact in power cable Check contacts of the power cable
SD - card is damaged Replace SD-card can be checked in Setup→Network Setup→Status→System Log messages
There is a infinite loop in Lua scripts, watchdog reboot triggered Check the communication log which script causes a watchdog reboot and correct the script

SD-card can be checked in Setup→Network Setup→Status→System Log messages . The error message looks like thie:

 Mon Apr 11 11:54:43 2016 kernel: [  110.790000] sd 0:0:0:0: [sda] Unhandled sense code
 Mon Apr 11 11:54:43 2016 kernel: [  110.790000] sd 0:0:0:0: [sda]  
 Mon Apr 11 11:54:43 2016 kern.warn kernel: [  110.790000] Result: hostbyte=0x00 driverbyte=0x08
 Mon Apr 11 11:54:43 2016 kernel: [  110.800000] sd 0:0:0:0: [sda]  
 Mon Apr 11 11:54:43 2016 kern.warn kernel: [  110.800000] Sense Key : 0x3 [current] 
 Mon Apr 11 11:54:43 2016 kernel: [  110.800000] sd 0:0:0:0: [sda]  
 Mon Apr 11 11:54:43 2016 kern.warn kernel: [  110.810000] ASC=0x11 ASCQ=0x0
 Mon Apr 11 11:54:43 2016 kernel: [  110.810000] sd 0:0:0:0: [sda] CDB: 
 Mon Apr 11 11:54:43 2016 kern.warn kernel: [  110.810000] cdb[0]=0x28: 28 00 00 0b 61 10 00 00 f0 00
 Mon Apr 11 11:54:43 2016 kern.err kernel: [  110.820000] end_request: critical target error, dev sda, sector 45744

Access troubleshooting

No access to WebHMI from browser

 WARNING! Be sure to save the password, when you change the default password, THERE IS NO project password 
 reset option in WebHMI (with the aim of protecting the intellectual property of project developers)|

Login/Password does not match

Possible cause Solution
Forgot or lost project / network setup password Clear the project from network settings menu. Do the network settings reset if neccessary.
Login or password is pasted from clipboard with extra space symbol. Enter correct data
Login or password entered in different language Use English layout for entering
You have enabled auto-fill option in browser setting so old/different password is loaded from browser cached data Clear browser's cache and enter correct data

Login/Password are Ok but nothing happens after input

Possible cause Solution
SD card is out of space Clean data log using ftp-access to 'log' folder
Browser session terminated after network disconnection Check the connection to the WebhMI and refresh the login page

It is impossible to load page in browser, ping exceeds timeout limit

Possible cause Solution
Damaged patchcord Replace the cable
Wrong IP-address of the WebHMI Reset network setting
if there is VPN connection up on the WebHMI, you may use it to check network setting
if there were complicate network setting and you don't want to do the network setting reset then:
a) plug in Ethernet cable from PC ( with DHCP client setup) to LAN port of the WebHMI and check gateway assigned to the PC's interface
b) Recall the subnet where WebHMI was used last time, assign this subnet IP address to PC network interface and use software IP-scanner to find it.
You are trying to connect via interface which set to WAN firewall zone in WebHMI, which restricts incoming connections Change firewall zone or settings for this interface in WebHMI
Your PC is now in two peer networks ( e.g. WiFi for WebHMI connection and Ethernet both are 192.168.1.x)Leave only one connection enabled for WebHMI or change network settings respectively
Your WebHMI is now in two peer networks ( e.g. WiFi for WebHMI connection and Ethernet both are 192.168.1.x)Change network settings respectively

Wi-Fi troubleshooting

Unable to connect to WebHMI via WiFi

Possible cause Solution
Wi-Fi access point is disabled Connect via LAN interface and turn on WiFi master interface
Weak signal in access zone- too far from WebHMI, EMI interference , Wi-Fi not in place Plug antenna, come closer to WebHMI where signal is stronger
There is probably another WebHMI with the same SSID for wireless network Change SSID for wlan on either WebHMI.

WebHMI can not detect another WiFi network

Wireless network has hidden SSID Add wireless network interface in WebHMI in manual mode.
WiFi network works on other radio frequency (e.g. 5 GHz).WebHMI supports frequency of 2.4 GHz. You need to change respective settings on wireless access point
Wireless network uses different radio channels In WebHMI, the frequency channels used are determined by the region selected in the wireless network setting. Perhaps the current setting does not have a channel that is selected on the access point. You must reconcile these settings.

Communication on RS-485

In order to save time, it is recommended to make sure beforehand that the peripheral device with RS-485 is not only configured correctly, but also responds to queries of the test program, or it's software tool. It is desirable to have an alternative serial communication device USB or RS-232 → 485 and a laptop (computer). Preliminary verification will save a possible loss of time for setting up a connection, if this is done immediately from WebHMI. In the case of several operating peripherals and one 'problematic', it is recommended to disconnect all connections for operating devices, and only work with one device being set up. Then analyzing the possible cause will be easier with the help of diagnostic LEDs RX TX. For example, if only the TX diode is lit, then only the transmission is working, and not any reception. If the RX diode works, but not “mirrors” TX LED behavior, there are reception failures. In the absence of errors, the diodes operate alternately at the same frequency.

The Error LED also indicates the presence of communication errors.

There is communication via standard tool (485 converter and software tool), but not via WebHMI

Possible cause Solution
Connection or register settings on WebHMI do not match those ones on device Make correct settings for 485 communication and register settings so to match with the peripheral device
The connection using 485 on WebHMI is disabled or switched into virtual COM modeEnable connection, switch virtual COM mode off
RS-485 port on the end device has hardware peculiarities (pull-up down resistors or voltage level check, terminating resistor needed, common signal ground wire is needed etc.) Put necessary resistors, use 3-wire circuit for RS-485.
The situation is possible when a 3G modem plugged into USB connector, and the system path (/dev/ttyUSB…) for 3G modem was chosen from already engaged device (serial port) (e.g. /dev/ttyUSB0 is used by the on-board RS-485), and network driver may interfere with serial port operation. Specify the correct system path for the modem in the network settings (you can see the path in the kernel messages, the menu Maintenance
Kernel Messages).
RS-485 port is damaged on WebHMI You can check the functionality of the RS-485 port of WebHMI by creating a Modbus ASCII connection on it, and instead of the peripheral device, connect a laptop or computer with a USB-485 converter and start the terminal utility or the 'Modbus Slave' simulator. In case of absence of exchange (absence of reception in the terminal) with simultaneous operation of the TX LED, it is possible to conclude that the port is damaged.

Unstable register read

Possible cause Solution
EMI on the RS-485 bus, bad contact Check the line (tightness of contacts, topology of the network - there should be a bus without radial branches, shielding - ground the shield at one point, the presence of terminating resistors of 120 ohms for RS-485, no shorts of the signal wires between each other and on the ground)
Communication rate too high Slow down comm. rate
Small timeouts waiting for a response from slower devices. In this case, the re-reading of the register begins with the 'belated response' from the device, which leads to a collision.Set a longer communication timeout
Peripheral device according to the documentation can work with different settings, however only a few of them work stableTry different comm. settings for the peripheral device

One of the registers can't be read or reading unstable

Possible cause Solution
Another (adjacent in polling queue) device after the end of transmission has a 'long' transient process, which leads to a distortion of the communication with this 'problem' device It is necessary for the connection, where the 'problem' register is located, to establish a greater 'stabilization time' (stabilization pause). Then before the communication in this connection starts, the necessary pause will be maintained.

Some of the registers in the working connection are not permanently readable

Possible cause Solution
Wrong register addresses Check register addresses. In the communication log (with the Debug and Trace levels set) for these registers, there will be detailed error codes and communication telegrams, which will allow to make thorough analysis of the cause.
The “Read On Demand” property is set for the registers Set normal or high priority for registers
The Strict scan option is set in the project settings, which means that the registers with the usual priority, which did not have enough time to be read, are excluded from the polling queue Increase scan time, disable strict scan option
The device to which WebHMI is connected supports only single or only double word exchange. By default, the polling driver uses the word (Word) reading to read registers of Double Word type, so the device may not respond to an unsupported type of command. Allow group read of Modbus registers into blocks of length 2 in the connection properties. Or vice versa disable it, if end device does not support multiple read operation


Program is not executed

Possible cause Solution
Program is disabled Enable the program
There is a runtime error Look through Communicatoin log. In the messages with ..lua script.. error line number is indicated
Program set to run upon register change/button pressing/calendar, but the run condition is not metCheck settings
Wrong program logic To simplify debugging, add debug printing (functions DEBUG, INFO, TRACE) with output of intermediate results in Communicatoin log

Wrong result of mathematical operations

Possible cause Solution
Lua has a limited accuracy for double type values to 54 bit. This can be noticable when processing very small or big numbers. Or storing certain decimal values which are “hard” to represent in a binary system without accuracy loss, e.g. 1.1 might look like 1.0999999999999999 Round intermediate results to reasonalbe accuracy
Put the math operation in the order they unlikely to cause overflow (e.g. first divide arguments and then multiply them)
For “true” double float operations use your custom function processing binary representation of the numbers

Running demo Virtual box image

No serial port available while editing connection properites

Possible cause Solution
USB-serial converter is not connected / Wrong driver is used / Converter is not working Check the converter is plugged and working in a host OS
COM port in the guest machine is mounted as a host COM port There is a compatibility issue under Windows for attaching Windows Com ports into Linux guest OS. Try to mount Usb bus device, not a Com port. In some cases, Usb Com port works only if they are added into Usb filtered devices in virtual machine settings. See the picture
Usb filter is set for the serial port, it is available in the list of the available usb devices for mounting, but error message appears upon attempt to mount it In Windows: Using regedit go to the following registry entry and delete the “UpperFilters” key. Reboot the host computer. The key resides in “HKEY_LOCAL_MACHINE > SYSTEM > CurrentControlSet > Control > Class > {36­FC9E60-C465-11CF-8056-44455354­0000}“

Can't import virtual machine due to existing uuid

If you have multiple webhmi images in Virtual box, you can encounter this error, becuase virtual image being added usually build based on previous one, so it may have the same uuid for itself or vdi files. For this, you can detect which machine has colliding uuid with the VBoxManage command line tool and in the virtual storage manager in Virutal Box.

Visualization issues

Dashboard editor

SVG image is not displayed during editing

The SVG file should have “width” and “height” attributes in the header. Otherwise it may hide while editing in some browsers, like FireFox, see the below picture:

Please reset the “responsive” property in your svg files.

Orphaned images

Image choosing popup in dashboard editor has orphaned images

If you accidentally deleted some images or folders with images directly from SD card - pass the /setup/images/list.php?orphaned parameter to url. System now will read list from databse (not directly from SD card), where deleted records still exists. Make the relevant changes to syncronize your records with really-exists images. Feature available since version

troubleshooting_faq.txt · Last modified: 2022/08/17 15:14 by emozolyak

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