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ASi Slave Comm Failure

Created by: Rick L at: 4/30/2008 5:56 PM (7 Replies)

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4/30/2008 5:56 PM	Rate (0)
Rick L Posts: 5 Rating: (0)	Hello, I have a Siemens S7224 PLC with CP243-2 ASi master. The application is a freight elevator door system. From my ASi master, I have one ASi legthat services 15 landings each withone F90 (4I/4O)slave and one legthat services the elevator car with two F90 (4I/4O) slaves. Each leg is approx. 300ft. in length. I have an extension plugafter my last slave on leg one (bottom floor). The PLC and Master are in a room above the elevator hoistway. After everthing running fine for about 1 month, the diagnostic led on the slave turns red (intermittenetly) indicating communication failure at floors 2, 3 and 4 only. I have called Siemens support and am still waiting for there return call from two days ago. My ASi line is standard 18ga in a10conductor bundle. I do have a shielded 220VAC bundle motor wire running in the same wiring trough. I currently have the mechanic switching the slaves from other floors to the problem floors to rule out slave issues. Any help would be greatly appreciated.
Rick L Posts: 5 Rating: (0)	Last edited by: Rick L at: 4/30/2008 5:58 PM
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4/30/2008 6:18 PM	Rate (0)
RICII Posts: 34 Rating: (0)	Hi Rick, I have had problems with running ASi in the same trunking as motor cables, the manuals suggest 150mm distance from any mains, especially PWM controllers (ie.drives, inverters) I had a similar problem and I ended up putting filter units on all the power supplies, even the ASi lines! Apparently the shield on the cables acts as an aerial, so I removed the shield to Earth connection RICII
RICII Posts: 34 Rating: (0)	Last edited by: RICII at: 4/30/2008 6:21 PM
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4/30/2008 7:07 PM	Rate (0)
Rick L Posts: 5 Rating: (0)	Thanks for the reply RICII. Ihave line reactors on the inverters. I didn't know you could filter the ASi line. Would that help? We have three similar elevator shafts in the same building using the same equipment with no problems. My company probably has about 10 to 12 of these high-rise freight units installed with all installations being typical and no comm problems including shielded motor wires in 1" conduit with ASi line. We were told to always ground our shields on the motors and back at the controller for the motor line. If there is ASi interference, why isn't it at the bottom floor (furthest slave from the master). Also, I just found out that one of my slave outputs on the 2nd leg is chattering (powers a contactor). Is there anything else that could cause comm problems with the slaves? Is my extension plug being used properly? Do I need other extension equipment?
Rick L Posts: 5 Rating: (0)
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5/1/2008 5:45 PM	Rate (0)
Rick L Posts: 5 Rating: (0)	More Information: The bottom 5 floors (furthest slaves from ASi master/power supply) lose communication when input 1 on the slave is high. The 10 floors above lose communication intermittently (red/green flash) when input 1 on the slave is high. I had mechanic ermove the slave and try close to ASi mater. When they did this, there was no communication loss. I assume that rules out slave problems. So maybe the issue is 1. The 3-phase 220VAC shielded motor wire is interfering with the ASi line or 2. The extension plug being used is not enough to send the signal and a repeater is required. Or 3......
Rick L Posts: 5 Rating: (0)
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5/1/2008 8:49 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Dear Rick, could you provide us a drawing of your configuration, at best with all length between the Master and the Extenders and between the Extenders and the Slaves. I think this will help a lot because reading the Text does not give a really good picture. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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5/2/2008 1:59 PM	Rate (0)
Rick L Posts: 5 Rating: (0)	Attached is very crude sketch of my application. It shows an elevation of a elevator hoistway with 6 floors (landings). It also shows the elevator car at the bottom landing. My application actually has 15 floors. So, the main controller (home of ASi master/psu) is above the elevator hoistway in the machine room. There are two ASi legs coming from the machine room. The 1st leg is 18ga unshielded that services 15 landings with one 4I/O slave at each landing. The 2nd leg is 18ga shielded elevator travel cable that services the elevator car which has two 4I/O slaves. Both legs are approx. 300ft. each. The Lowest slave on leg 1 has an extension plug. I have no repeaters or extenders in this configuration. Thanks. Rick Attachment Elevator_Sketch.pdf (457 Downloads)
Rick L Posts: 5 Rating: (0)
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5/2/2008 11:05 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Dear Rick, at the moment, because I do not know all about your setup I would try to change the configuration. I would do the following, add a AS-i Repeater, to split the Network, right besides the AS-i Master. Well, you are right that way you have to add an additional Power Supply too, but I think to ensure, because you reach the border at 200 m really closely, the electrical stability the use of a Repeater is essential. This is my opinion, if someone else has another one I look forward to discus it. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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5/5/2008 6:04 PM	Rate (0)
Rick L Posts: 5 Rating: (0)	Up and running with a new extension plug. I really don't think the installers were listening to me when I said switch out the extension plug from one of the operational installs. Oh well, at least were are working now. Thanks for all the help.
Rick L Posts: 5 Rating: (0)
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