In early morning, there is a report that said our SCADA,that named WINLOG in trouble. Error display was 0 in all parameter display. Instrument personel reported that nothing trouble in yesterday. Its because a rainy ?
After see to the field, the screen display just show the zero number in all display boxes. I think there is a problem between PLC and Display. But We must localized one by one to solve the problem.
The only way to know that PLC worked as well is : We must online with PLC. For safe trouble shooting, do online with USB cable if the PLC was available.
Now we do online with PLC via USB cable. Use the laptop for easy solving.
MAPPING THE PROBLEM: 1. CONTROLLER SIDE. 2 COMPUTER SIDE
After we do online with PLC via USB cable, its looks like that PLC was worked as well. Nothing problem. The number was floating inside the memory. It mean there are no problem in Controller side, but there is a problem is Display/ Computer side.
But the problem could also came from the IP address of Modbus module. How do we know that the MODBUS module is working as well? The answer is just chek the parameter inside the pheriperal setting at PLC menu. Look at the CX Programmer menu setting.
The next step is make sure that the setting was correct at tab pheriperal service.
The next step is do check the number of IP address that used by PLC. To know the IP address, just look the number of memory addresses of D1200 and D1201. Look the image below. In online mode, select the monitoring mode, click the icon Memory in work space area, choose the D memory, and scroll it until you find the memory address D1200.
Look at the memory D1200 and D1201. The PLC said D1200=C0A8, D1201=FA0B. If we read it, the code will be like this: C0 – A8 – FA – 0B ( Hexadecimal number ).
IF you calculate of the serial number, it will be like this: 192 – 168 – 250 – 11. It mean the IP address of your MODBUS TCP module was that number.
The next step is, we must ping the address of PLC’s modbus module as well. Make sure that your laptop and the PLC was online with the LAN. Make sure that your PLC and laptop was in the same subnet group. It must be pinging and must be TTL also.
In this case, IP address of the laptop is 192.168.250.2
Open the Prompt command . Do ping the module with typing : ping 192.168.250.11 and execute with Enter button in your keyboard .Just like the image below:
If you got the TTL value ( TTL=64), it mean your PLC module was okey. It can called and read. Now we try to check the memory inside the PLC. In this article, I use a software name MODBUS POLL from WITTE SOFTWARE. The software was trial for 30 days.
After using the MODBUS POLL, we had a summary that Module was okey. It can read and translate the number in memory address of PLC. The Temporary conclutions is: PLC working well as the Slave of MODBUS TCP.
PROBLEM SOLVING AT COMPUTER SIDE
From here, we are knowing where the problem is: computer side or computer display. We must check the PC first time with do ping the ip address of PC.
In this case, the IP address if PC is 192.168.250.245. Now make sure that LAN cable was connected between Ethernet Hub to LAN port of the PC.
Do ping the PC with your laptop. Just type at command prompt: ping 192.168.250.245
In the image above we got information that the PC can not answer the ping. The detination was unreachable. Do check the IP address setting of your ethernet card or network card.
We must look the control panel of this PC to knowing the information of IP address of the PC. Just look at the menu Open Network and Internet setting from your right corner of the task bar.
WINDOWS 10: Start from menu Open Network and Internet Setting> Change adapter option> (choose) your ethernet name> (right click) Properties
WINDOWS 7: Starting from menu Open Network and Sharing Center> Change adapter setting> (choose) your ethernet name > (right click) Properties
You will be shown the LAN Properties.
In here, we know the PC has an IP address 192.168.250.245. But why still can not online?
Theres only 2 possibility:1. Ethernet card problem or 2. Connection cable problem. The easiest way is just check the lamp of your LAN Port of your PC,
After we check the port, look the LAMP indicator of ethernet port. In this case, the lamp is OFF. It mean there is a problem with your cable. The simple way to make sure the cable is, replace the cable. But if you have not a spare cable, you must check the whole the end of the cable.
Yeah. The cable was Cutted of . its cutted off bitted by the Rat.
After the lamp of LAN port was switch ON, now we look at the display.
The display show the number. It mean the SCADA can run well. Problem solving end. Thanks for reading.