Profibus problem

idell · Apr 27, 2010

Hi!
Recently i've met one problem in our system.
I will describe system : CPU 313C-2DP (6ES7 313-6CF03-0AB0) & 8 IM151-1 Basic (6ES7151-1CA00-0AB0), connectors - 6ES7972-0BA12-0XA0, profibus cable 6XV1830-0EH10 (can see topology of network in attached file)

All stations work fine when the speed is configured 187.5Kb/s, need to increase speed and now appear problems:
Speed 500Kb/s - work stations nr 1,2,3,4,5,6,7
Speed 1,5MB/s - work stations nr 0,1,2,8
More than 1,5MB/s - only station 1 works.

What could be the problem?

Jobbe · Apr 27, 2010

Did you check the termination resistors on the connectors? They should be ON at station 8 and 7, and OFF on all the other devices.

Also make sure that you connect the cable at device 7 and 8 on the "ingoing port".

What is the total cable length of this network?

idell · Apr 27, 2010

Thank Jobbe for fast response

Did you check the termination resistors on the connectors? They should be ON at station 8 and 7, and OFF on all the other devices.

Resistors of stations 0,1,2,3,4,5,6 are OFF, of stations 7,8 are ON

Also make sure that you connect the cable at device 7 and 8 on the "ingoing port".

so it is.

What is the total cable length of this network?

aprox. 120-130m.

Maitomies · Apr 27, 2010

Hi,

I once had some problems with profibus devices also. Turned out that the switch controlling terminal resistor inside the connector had "slipped" and was really not changing the state of the resistor. I noticed that when I opened the connector.

One other simple way is to activate all terminal resistors and then one by one turn them off starting from the master to determin which station/connector is causing the problems. 1,5MB/s max cable lenght is 200m, so I would not use higher speed.

JesperMP · Apr 27, 2010

Jobbe said:
Also make sure that you connect the cable at device 7 and 8 on the "ingoing port".

idell said:
so it is.

Not if you diagram is an accrurate representation of how the cable is laid, and how it enters the connectors. In slave 8 it is shown to go into the out-going arrow.

Generally:
If only 1 cable enters the connector, it MUST enter at the in-going arrow.
If 2 cables enter the connector, it is generally recommended that the side that is closest to the master enters at the in-going arrow.

idell · Apr 27, 2010

JesperMP i've made mistake in diagram, tomorow I will try Maitomies advices, thx

JesperMP · Apr 27, 2010

You can disconnect slaves 7 - 1 (in that order), and see if the problem follows one or more of the slaves.
It is not possible to disconnect slave 8.

idell · Apr 27, 2010

JesperMP what do you mean disconnect ? to pull out the connector or to turn off power supply ?

Jobbe · Apr 27, 2010

idell,

You can also do a few simple measurements with a multimeter. At least if you can turn off the system.

Download the PROFIBUS guideline on this link:
http://www.profibus.com/nc/downloads/downloads/installation-guideline-for-profibus-dpfms/display/

..and check out chapter 4.

But try the method from Maitomies first.

JesperMP · Apr 27, 2010

idell said:
JesperMP what do you mean disconnect ? to pull out the connector or to turn off power supply ?

I mean changing the switch on each connector to the ON position. This turns the terminator resistors on, and disconnects the out-going cable.
For example:
By changing the switch on the master CPU to ON, all slaves 1-7 are disconnected.
Or, changing the switch on slave 3 to ON, all slaves 4-7 are disconnected.

Nick B · Apr 27, 2010

Jasper is correct. You need to be going into the IN Hole. The way you have it your not terminated even if it is switched on (NODE8).

idell · Apr 28, 2010

The problem was in the connector of station nr.3, there cables were swapped (cable IN was from 4st. and cable OUT to 2 st.) i changed and system begin to work.

One other simple way is to activate all terminal resistors and then one by one turn them off starting from the master to determin which station/connector is causing the problems. 1,5MB/s max cable lenght is 200m, so I would not use higher speed.

Maitomies - distance segment CPU->st.7 has 10 m/per node, distance between CPU and st. 8 is 35 m. current speed is 12Mb/s. Thanks to all for replies.

Jobbe · Apr 28, 2010

The problem was in the connector of station nr.3, there cables were swapped

It doens't matter if you swap the cables if you connect them both and don't use the termination. Maybe there was a bad connection in that connector?

current speed is 12Mb/s.

A 12 mbit network is verry sensitive for errors. 99% of all PROFIBUS systems do not require this high transmision speeds. Are you sure you want to keep it this high? I usually set it at 500 kbps standard. The max cable length at 12mbit is 100m and stub lines are not allowed, not even to connect a laptop!

idell · Apr 28, 2010

Jobbe on st. 2 we have 1 ModBUS module master with 32 slaves, now request of slaves is done much faster than speed 500kb/s

JesperMP · Apr 28, 2010

I think you have more problems than that the cable was swapped between in and out. As long as the terminator is set to off, then it should not matter.

Beware that at 12M profibus is unforgiving. Example is that some profibus cables will not work, even if they are stamped to be approved for Profibus. You also cannot just attach or remove a laptop. Because of this I have never gone above 1.5M.

Profibus problem

idell

Member

Jobbe

Member

idell

Member

Maitomies

Member

JesperMP

Lifetime Supporting Member + Moderator

idell

Member

JesperMP

Lifetime Supporting Member + Moderator

idell

Member

Jobbe

Member

JesperMP

Lifetime Supporting Member + Moderator

Nick B

Member

idell

Member

Jobbe

Member

idell

Member

JesperMP

Lifetime Supporting Member + Moderator

Similar Topics