CC LINK Communication Error

[Areeb 0]

Hi everyone ! Hope you are doing good. I have one query related to CC Link Modules. I have a machine which consist of Mitsubishi Q Series PLC and with that there is also a CC Link module in which there is a loop of individual Communication Station. But the problem I am facing is that sometimes 2 of the communication stations gave communication error randomly, sometimes it works fine for about week or months but sometimes they will give error after one hour or two hour or 1 day. I did not understand the exact cause of this error whether it coming due to large length of wire between the stations or module faulty etc . can anyone let me know why this error occur and what might be the possible causes of this error.

Thanks & Regards

Areeb

 

 

[sczot 4]

hello, you would have to share more details, but i would start checking cables and connectors

[Zamora 0]

Does it give out a specific error code? Also, what kind of CC-Link module are you using?

As sczot stated, I would recommend checking the state of the connectors and cables, maybe you are finding a fault because of a false contact that fails every once in a while. A possible cause may be overlapping station numbers or incorrectly set station switches. Check that the stations are receiving the correct power voltage and that the transmission rates (baud) are set properly.

If worse happens, maybe a Master or Slave station is malfunctioning.

 If you can, look up the troubleshooting guide for your I/O module. In my case I have QJ6BT11. I am not sure if we can link to these files but it shouldn't be hard to find it online.  In this case, ERR LED status will be useful in checking the problem.

Best regards

[Areeb 0]

Thanks all. I am using QJ61BT11N (Master) which is connected with PLC and all othe slave stations are AJ65SBTB-16DT and usually slave stations gives error and LERR light will blink. Furthermore I have check all the stations no and setting it is fine.

[sczot 4]

according to mitsu manual  (chapter 8.1) when LERR is flashing its caused by conection cables

[Areeb 0]

ok but I wanted to know one more thing which is that in order to solve the above problem we need to shorten the  length by placing the module with their neighboring modules (because the error will give only  those modules which are far away with other modules) or we just replace the communication cable of these modules. 

[Areeb 0]

OR sometimes this issue will gone when we take out the terminating resistor from the last module and then again place it in the module. we are using resistor of 120 ohms.

[Zamora 0]

What is the distance between your stations? Maybe you are going over the recommended transmission distance. If this may be the case you could solve the issue by installing repeater stations.

[Areeb 0]

@Zamora I do not exactly know the distance but this might be the issue. can u please tell me what is repeater station and how to install it ? 

[Zamora 0]

On ‎2020‎-‎07‎-‎24 at 0:26 AM, Areeb said:

OR sometimes this issue will gone when we take out the terminating resistor from the last module and then again place it in the module. we are using resistor of 120 ohms.

Checking the QJ61BT11 Manual, its says that the terminator resistor should be 110 ohm in case of CC-Link dedicated cable and 130 ohm in case of CC-Link high performance cable. Please check that the terminating resistor is of the correct capacity.

Also, depending on the transmission speed and version of CC-Link you are using (Ver. 1.00 or Ver. 1.10) the maximum cable length changes. Please check the approximate distance between stations to maintain your cable length within these parameters.

In the case of Ver. 1.10, depending on the transmission speed, this is the maximum TOTAL cable distance (sum of length of all cables between stations):

• 156kbps = 1200m
• 625kbps = 900m
• 2.5Mbps = 400m
• 5Mbps = 160m
• 10Mbps = 100m

Also, please make sure that you are using the dedicated CC-Link cable, otherwise transmission fidelity is not guaranteed.

6 hours ago, Areeb said:

@Zamora I do not exactly know the distance but this might be the issue. can u please tell me what is repeater station and how to install it ? 

Please verify that distance is your issue before purchasing and installing a repeater station. As the name implies, a repeater station is meant to extend the transmission distance capability of the CC-Link system. I recommend you look up the manual for "CC-Link System Repeater (T-junction) Module AJ65SBT-RPT" for more information about the module and if this is indeed the right option for you.

 

[Areeb 0]

Thanks alot @Zamora. Hope this information will solve this problem.