jh07052

CC-Link Network Dropping Out Ideas?

5 posts in this topic

The CC-Link system on a machine has been intermittently dropping out.  Normally the Link Scan Time runs at a solid 87ms.  When the system "drops out", the link scan time will increase.  Sometimes double, triple, or go up 10x. It happens when the machine is running or when it sits idle.

There are 33 stations on the network.  The same stations do not always fault but sometimes all of the stations will fault at once (as seen in the attachment pictures.)

We have changed the main QJ61BT11N, the processor, the Q62N power supply, the main backplane (base unit), all cards on the main backplane. 

Is it possible for one station or one of the cables to create a network wide problem?  Any ideas thrown at us would be appreciated. 

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I experienced exactly the same problems that you are having a few years ago.

Sometimes there seemed to be a pattern to the faulty stations but despite swapping out various stations both digital in/out and analogue in/out and the BT11N the problem would always return at some random time.

I had been assured by the electricians that they had carried out a terminal tightness check on all the stations prior to me being called to site.

In desperation after a month of random failures I instigated another wiring check and found a loose connection at one of the stations that was particularly awkward to get to.

I can't remember whether it was DA, DB or DG but once tightened the fault never occurred again.

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16 hours ago, jh07052 said:

The CC-Link system on a machine has been intermittently dropping out.  Normally the Link Scan Time runs at a solid 87ms.  When the system "drops out", the link scan time will increase.  Sometimes double, triple, or go up 10x. It happens when the machine is running or when it sits idle.

There are 33 stations on the network.  The same stations do not always fault but sometimes all of the stations will fault at once (as seen in the attachment pictures.)

We have changed the main QJ61BT11N, the processor, the Q62N power supply, the main backplane (base unit), all cards on the main backplane. 

Is it possible for one station or one of the cables to create a network wide problem?  Any ideas thrown at us would be appreciated. 

Normal.jpg

drop_ex1.jpg

drop_ex2.jpg

drop_ex3.jpg

I installed and commissioned a multi arm rotational machine cc- link ran to the five arms with 3 stations/arm cc-link ran through a set of slip rings I used a FX 3U and have not had a problem yet in 3 years continuous running. I would look at the cabling as a first port of call. Good luck.

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I had a similar symptom 2 years ago.

We had a terminating resistor installed across DA-DG instead of the correct DA-DB. 

Just one more option to check. 

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I did a stone quarry over a decade ago where I ran CC-Link cable over 600 feet tied to conveyors and overhead cable to one remote temperature input station...  It worked before I even had the terminating resistors installed.  Never lost communication.  Make sure the cables are tight and the shield is properly grounded on one end...

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