PF755 & compactlogix; Control 8 drives at the same time. somt. a drive wil not move

PF755 & compactlogix; Control 8 drives at the same time. somt. a drive wil not move

Controlling 8 drives at the same time. Sometimes 1 drive will not move?

We have at the site an installation to move a deck. Therefore we need to control 8 drives at the same time.
We have a compactlogix L30ER and in total 8 Powerfelx 755 drives.
In our software we have 1 master drive and we copy the control data to each drive. We use the status data off all drive to check if everything worked ok.

3 of the 4 times everything works fine. We are able to home, to jog and to move to a position. But sometimes 1 or 2 of the drives will not move.
At this point we have no clue what causes this strange problems. Does anyone have an idea?

The compactlogix L30ER communicates trough Ethernet with the drives, and the drive cabinet is 30 meters from the controller cabinet.

Tell us about what ethernet switch you are using.

We use all rockwell material.

In the cabinets we use: 1783-US08T --> Ethernet switch,Stratix 2000,8 Port,Unmanaged, Copper Ports,10/100 M


And we make a ring in fore the field with the ETAP modules: 1783-ETAP --> EtherNet/IP Tap, 3 Port,Copper,10/100 M

It seems like noise, have you used wireshark, download it.
Go to http://www.wireshark.org/
This software allows to identify what problem you have.

We used fluke networks.
see attached picture

When looking for noise problems, I would go directly to the embedded web pages for the drives themselves; a lost packet for noise reasons will show up there for certain, but may be harder to find in the timeouts or packet statistics in the CompactLogix.

HTTP service availability, as shown by that Fluke tool, doesn't mean very much.

I would also check the way you do the logic, specifically how you manage the STOP bit.

The STOP bit will over-ride the START bit, so you need to make sure there is no way for both to be true at the same time. If you have the STOP bit true whenever the START bit is false, there is a possibility for the output data to be sent to the drive in between the instructions that set those bits.

Tanks for the responses Wildelto and Ken Roach.

I will look into the noise problem at Monday.

The problem occurs also with jog1 command. the JOG1 command is an interlock in the start and stop bit. When we start to Jog, both start and stop will be forced to false (if they were true).
In our program the start and stop bit will be controlled by a sequencer, so there will be only one bit true.