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Old January 10th, 2020, 03:10 PM   #1
Stuwertz
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Power flux error 71 on devicenet network

I have running devicenet network consist of 1796-SDN and 14 powerfexes, three consits of power flux 700 and remaining consits of power flux 40 .
The problem is during the line operation F71 occurs occasionally on different Powerflex screen drive.it is appears on alternative drives them but not in same time .
I replaced the two of powerflexs ,checked the cabling but without hope .


Could any one please help on this ???
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Old January 10th, 2020, 04:03 PM   #2
Ken Roach
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Does a network error code also appear on the DeviceNet scanner or in its Status tags, as well as on the drives ?

Does the fault reset by itself, or must you perform a power cycle to clear it ?

Does the "F71" code appear on the PowerFlex 700 drives, or only on the PowerFlex 40 drives ?

The fault code "F71" is "Network Loss Fault" on the PowerFlex 40 drives.

In general, this can be due to loose wires or interference with the CAN network signal on the DeviceNet, or due to interference or damage to the 22-COMM-D connection to the drive itself.

"Check the cabling" requires an oscillosope or measurements; visual inspections will not show interference.

One easy thing to check is the termination resistors. Power off the DeviceNet 24V DC power supply, and measure the resistance between the blue and white wires. It should be a little less than 60 ohms, indicating that both of the 120 ohm terminating resistors are in place.
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Old January 10th, 2020, 04:30 PM   #3
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Hi mr.Ken

Please find the answers on each questions



Does a network error code also appear on the DeviceNet scanner or in its Status tags, as well as on the drives ?
While error on power flux drive, in devicenet scanner also showing 78 and error appeared power flux node number



Does the fault reset by itself, or must you perform a power cycle to clear it ?
No .I need to restart a power to clear the error.



Does the "F71" code appear on the PowerFlex 700 drives, or only on the PowerFlex 40 drives ?
Both power flux 70 and 700.



The fault code "F71" is "Network Loss Fault" on the PowerFlex 40 drives.

In general, this can be due to loose wires or interference with the CAN network signal on the DeviceNet, or due to interference or damage to the 22-COMM-D connection to the drive itself.

"Check the cabling" requires an oscillosope or measurements; visual inspections will not show interference.

One easy thing to check is the termination resistors. Power off the DeviceNet 24V DC power supply, and measure the resistance between the blue and white wires. It should be a little less than 60 ohms, indicating that both of the 120 ohm terminating resistors are in place.

I measured the reisitance it shows around 160 ohm .





Before we had an same scenario then we replaced one by one power flux drive then after replaced one drive the issue got solved. Nut now we have 14 drives we don't have time to replace one by one.We know that in the 14 available drive one is faulty. Is there any other way to find the faulty drive.
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Old January 10th, 2020, 05:13 PM   #4
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Quote:
I measured the reisitance it shows around 160 ohm .
DeviceNet networks require two termination resistors of 120 ohms each, connected between the CAN_H and CAN_L wires (Blue and White for DeviceNet) at the physical extreme ends of the network trunk.

Unlike Profibus, most DeviceNet products do not have a built-in termination resistor or simple switch to enable a terminating resistor. Most DeviceNet networks that involve VFDs use open-style connectors, and the resistors are easily visible wherever they are installed.

Because the CAN signal itself will interfere with an ordinary multimeter, you should shut off the DeviceNet 24V power before making this measurement.

Two 120 ohm resistors in parallel will give a combined resistance of 60 ohms; that is an ordinary Kirchoff's Rule calculation. The additional resistance of the DeviceNet transceivers makes the total parallel resistance a little less; a system with 14 drives should be measured at about 50-55 ohms.

A measurement of 160 ohms suggests that no terminating resistors, or resistors of the incorrect value, have been installed.

DeviceNet will often run without terminating resistors installed, which leads some users to believe that they are not required. This is not true, and you should do no more troubleshooting until you have verified that one 120 ohm terminating resistor has been installed at each physical end of the DeviceNet trunkline.

Two resistors. 120 ohms each.

Not zero, one, or three.

Not 150 ohms, or 82 ohms.

Last edited by Ken Roach; January 10th, 2020 at 05:18 PM.
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Old January 10th, 2020, 05:21 PM   #5
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F71 on a PF70/700 means there is a general fault on the DPI device that is plugged into Port 1, you must look at the device event queue of the DPI device itself to see what that fault was. Most likely though you have the HIM plugged into Port 1, so that is where I would start. If the HIM is remote mounted, it's probably a loose connector due to vibration or maybe intermittent moisture or corrosion.
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Old January 11th, 2020, 03:04 AM   #6
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Hi mr. Ken .



I checked that one resistor terminated on physical extreme end. I will double check the exact resistance values and how may resistors connected then i will update to you. Thanks.
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Old January 13th, 2020, 05:20 AM   #7
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Hi mr ken .

I checked in devicenet remove able devicenet female connector itís seperate two lines . In one line resistor connected at end . But in other line There is no resistor . Is there any rule that resistor should connected on last node as per the scan list . In my scanner 14 drives . 12 drives connected in one line ( except 4&6 ) . Two drives connected in other line ( node number 4&6 ) in this line there is no resistor at end . So my resistor need to connect on node no 14 . Thanks in advance.
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Old January 13th, 2020, 06:31 PM   #8
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Thank you for posting those results !

Double-check the resistor that is in place now; it should be 120 ohms.

The DeviceNet Media Planning Guide has good illustrations and calculations for how to plan and install DeviceNet wiring:

https://literature.rockwellautomatio...m072_-en-p.pdf

The location of the terminating resistors on a DeviceNet system is independent of the scanner location or the node numbers or the scanlist. The resistors should go at the physical ends of the network.

An example:
Attached Images
File Type: png DNet_Termination.PNG (15.4 KB, 39 views)
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Old January 14th, 2020, 04:59 AM   #9
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Hi mr. Ken ,

Today I installed resistor and I checked the values between can H and can L it shows 61.3 ohms . But again itís bad luck to us we are facing still F0071 on alternative drives.
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Old January 14th, 2020, 01:21 PM   #10
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Please confirm which drives you are seeing this fault code on: PowerFlex 70, PowerFlex 700, or PowerFlex 40 ? Your posts have not been clear about that.

As my colleague jraef has pointed out, a fault code "71" has a slightly different meaning on the PowerFlex 40 than it does on the PowerFlex 70/700.

On the PowerFlex 40, the LED display "F71" indicates a "net loss" fault, which does indicate noise or loss of signal on the DeviceNet. This is distinct from the fault "F81" that indicates a loss of connection on the ribbon cable between the 22-COMM-D module and the PowerFlex main control board.

On the PowerFlex 70/700, the "- Fault - F 71" display indicate that there's been a communication failure between the device on DPI Port 1 and its network. This is distinct from the "- Fault - F 81" code that would appear if the device on DPI Port 1 stopped talking to the drive or was unplugged.

"DPI" is the "Drive Peripheral Interface" protocol and wiring that PowerFlex 70/700 drives use to connect to network modules and keypad "HIM" modules. The DPI port number is based on where the device is physically plugged into the drive.

On PowerFlex 70/700 drives, DPI Port 1 is the onboard HIM cradle. DPI Port 5 is the 20-COMM-D module.

It should not be possible to get a "- Fault - F 71" fault related to the DeviceNet interface on a PowerFlex 70/700 drive. That would be fault code 75, not 71.

If this is a system that lacked proper termination, it is probable that it also has other wiring problems like a noisy power supply or loose connectors. The DeviceNet cable planning and installation guide has good information on how to properly power a DeviceNet and install the wiring.
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Old January 14th, 2020, 03:03 PM   #11
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Quote:
Originally Posted by Ken Roach View Post
Please confirm which drives you are seeing this fault code on: PowerFlex 70, PowerFlex 700, or PowerFlex 40 ? Your posts have not been clear about that.

As my colleague jraef has pointed out, a fault code "71" has a slightly different meaning on the PowerFlex 40 than it does on the PowerFlex 70/700.

On the PowerFlex 40, the LED display "F71" indicates a "net loss" fault, which does indicate noise or loss of signal on the DeviceNet. This is distinct from the fault "F81" that indicates a loss of connection on the ribbon cable between the 22-COMM-D module and the PowerFlex main control board.

On the PowerFlex 70/700, the "- Fault - F 71" display indicate that there's been a communication failure between the device on DPI Port 1 and its network. This is distinct from the "- Fault - F 81" code that would appear if the device on DPI Port 1 stopped talking to the drive or was unplugged.

"DPI" is the "Drive Peripheral Interface" protocol and wiring that PowerFlex 70/700 drives use to connect to network modules and keypad "HIM" modules. The DPI port number is based on where the device is physically plugged into the drive.

On PowerFlex 70/700 drives, DPI Port 1 is the onboard HIM cradle. DPI Port 5 is the 20-COMM-D module.

It should not be possible to get a "- Fault - F 71" fault related to the DeviceNet interface on a PowerFlex 70/700 drive. That would be fault code 75, not 71.

If this is a system that lacked proper termination, it is probable that it also has other wiring problems like a noisy power supply or loose connectors. The DeviceNet cable planning and installation guide has good information on how to properly power a DeviceNet and install the wiring.

Hi ,

We are facing f71 error on power flux 40 drives. And also now the one resistor connected on node 12 but physical end . Either it should be node 14.
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Old January 14th, 2020, 04:35 PM   #12
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Thank you for that clarification.

The "F71" fault code on a PowerFlex 40 drive indicates a signal or media problem on the DeviceNet.

I can only refer you to the DeviceNet Media Planning and Installation Guide.

The termination resistors go on the physical far ends of the network.


The node number, the type of device (drive, PLC, etc), and the scanlist order do not matter.
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Old March 3rd, 2020, 12:19 PM   #13
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Thanks everyone those your inputs. In final we replaced that power flux 70 drive then issue solved .



How we found that power flux 70 only having issue ? Two months before this power flux 70 inverter showed Earth fault. Then we replaced new inverter. It's working fine. The removed inverter we sent to local vendor to repair that power flux drive 70. He replaced power module.Then again we fixed this serviced inverter in to the loop. After this ceretain period only we are facing this error. So we replaced again new ,the issue solved.



It would help others also in future if they faced same error.
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