Hello,

I have a project with s7-300 PLC with around 60 number of simocodes.

Now, master is not available. But profibus networking is done for all slaves.I wanted to connect @ one ponit of network and access all other simocodes for commissioning purpose. Is it possible without having master in the network? Am using cp5711,for each  simocode unique address is assigned.

Hi,

 anyone tried this way ? because my colleague went to site and he complained that maximum 13 node only he is able to read using cp5711. Is any restriction is there like if master is not in network ?

no there shouldn't be any restrictions, has he set the Option " only master" at cp-config? have he tried another acesspoint, did he gets other reachable devices with another acesspoint? Are all Profibus-resistors set the correct way?

Hai,

sorry for delay in reply and thank you for the suggestions..

Settings are proper for termination and cp5711 setting.

master on the network is check marked.

speed is set to 1.5mbps

termination are ok on profibus connector

total length is max 30 meter

he will be visiting site again after a week, i will post the update here..

Hello gentlemen;

Profibus segment limitation is defined this way: a segment

- may contain a maximum of 32 nodes between terminations (this does not vary with bus speed);

- will be limited to a length that depends on bus speed: 100 m @ 12 MB for example.

So, in he proposed network of 60 slaves communicating at 1,5 MB, there must be 2 segments (with at least one repeater) to handle more than 32 nodes, and with a bus length of 30 m there is no bus speed limit, 1,5 MB is fine..

That being said, there must always be at least one master on a Profibus network for data exchanges to be implemented. The CP may be a physical master, and the only master on the bus, appropriately, but what software do you use to configure the bus? How does it connect to the CP?

Hope this helps,

Daniel Chartier

Dear Dchartier,

Thank you for the attention and suggestions. 

Currently total slave we are trying is 20. In my first post, I forgot to mention that. He could able to communicate up to 13th node. If he makes 13th node termination off and 14th termination on, then none of the nodes are detecting.

Thing is that, during fat there was a master connected to simocode. From pg/PC interface, he could able to detect all the nodes. Now this system is going to connect with another master. Before connecting to that customer want to see that all the nodes are accessible. Without a master in the network I haven't tried this before and am not sure will it work or not. 

So I just need a clarification that without master controller will this detection method work or not..

He used simocode software for setting address if all simocodes with simocode cable..

Hello vipz;

All right; you have 20 nodes connected properly on Profibus, and you connect a Profibus master with a complete configuration of all slaves somewhere before node 13, and it sees all nodes up to node 13.

Does your master have access to diagnostic information on the network? What do they reveal?

Changing the termination on nodes 13/14 results in a total loss of the network, correct? This will happen when termination is not active/powered up at the end of a network (this is a hint for conclusions to come later).

What does the master see if it connects at the other end of the network, say around node 19 or 20?

My instinct tells me that the master will see nodes between 14 and 20 when he is connected after node 14;  add to the fact that termination around nodes 13 and 14 seems to be lost when the resistor is activated, as shown earlier;  if that is the case there is probably a connection problem (short circuit on the Profibus cable, inversion of cable wires (Red/Green), loss of grounding connection) around or at node 14.

Do the same tests and evaluations on site and try to narrow the culprit node down as best you can.

This is a very frustrating type of problem and sometimes it will be very hard to find the exact location/source of the problem without some kind of Profibus analyzer (BT200, Amprolyzer, Profitrace from Procentec...). The fastest way to repair such a situation, if your tests determine a probable node as source of the fault, is to brute-force replace all cabling and connectors going to/coming from that particular node.

Hope this helps,

Daniel Chartier

Dear Dchartier,

Thank you for the suggestions..

I think there is some misunderstanding in the post. during FAT there was a master PLC in the network. Currently master is not there, only cp5711 is there with us. Connecting to a network where there is no master PLC and trying to read nodes using set/pg PC interface -> read option will work ?

This the point I need to clarify before going to site..

Hello Vipz;

You need  some kind of Profibus master to read the satus and diagnose the Profibus network. A CP 5712 will give you access to the Profibus network, but will not generate the software functions required to turn the PC into an actual Profibus master

The easiest way of course would be to have access to a S7 CPU with Profibus master interface, that you could configure with Step 7 or TIA Portal for this test.

The only other option would be some version of a Profibus master simulation program. Pepperl & Fuchs, Anybus and others provide this, but it must generally be purchased, along with their own access card for Profibus. Siemens to my knowledge does not sell one. Here are some links from the web:

PROFIBUS master simulator VAZ-PB-SIM - Pepperl+Fuchs

PROFIBUS Master Simulator - Bihl+Wiedemann GmbH

Profibus-DP/DPV1 - Master Simulator - Anybus

Hope this helps,

Daniel Chartier