How to configure CM1242-5 Profibus DP Slave as a standalone system

Hello all;

If there is a configured DP-master but no available DP-slave for the moment, you can program a SFC 12 "D_ACT_DP" block in the master so the slave address is removed from the polling list of the master.

This will reduce the number of faults due to the abscence of a slave on hte network on the network considerably.

Enabling a disabled DP slave with SFC 12 'D_ACT_DP'

https://support.industry.siemens.com/cs/ww/en/view/19730984

Once the slave is available, use D_ACT_DP once again to enbale the slave on the master's polling list.

Hope this helps,

Daniel Chartier

Alvin Chee

Dear Moilosh,

Lets assume there's no Profibus master in the network at the moment when i configure and download the S7-1200 program. Why is this error prompted?

-CPU error: New I/O access error during process image update /n input 2 (1 Bytes) will

temporarily not be updated as part of the updating of process image 0.

Isn't the CPU suppose to process the io area regardlessly ?

Thanks,

Alvin

 The module reads and write to the Process image of the CPU that is why i think 

dchartier

Hello all;

If there is a configured DP-master but no available DP-slave for the moment, you can program a SFC 12 "D_ACT_DP" block in the master so the slave address is removed from the polling list of the master.

This will reduce the number of faults due to the abscence of a slave on hte network on the network considerably.

Enabling a disabled DP slave with SFC 12 'D_ACT_DP'

https://support.industry.siemens.com/cs/ww/en/view/19730984

Once the slave is available, use D_ACT_DP once again to enbale the slave on the master's polling list.

Hope this helps,

Daniel Chartier

Hi dchartier

From the documents on this module  .No instructions orsoftware blocks are required for this. The I/O data is read or written directly from/to theprocess image of the CPU 

so will the method work in this case because i think this seems to be unique in the manner that it reads and writes to Process Image 

Hello qwemx;

Your question is not quite clear to me. Let's start by clarifying some ideas.

Profibus-DP (Distributed Periphery) is a fast, cyclic data exchange between a master and a slave, where the data recovered from the slave is written to the master's input area, and the data written to the slave comes from the masters output area. This link between I/O areas of the master and slave is configured directly in the hardware configuration of the master, using the gsd files for each slave describing the slave's I/O capabilities.

SFC 12 "D_ACT_DP" is a system function for distributed I/O (Profibus-DP or Profinet communications). You can see its description in the System and Standard Functions manual for S7-300/400 CPUs; if you are working with TIA Portal, look at the online help in Step 7 for a similar presentation on the function D_ACT_DP.

https://support.industry.siemens.com/cs/me/en/view/109751826

As you can see in the screenshot below, D_ACT_DP removes the selected slave from the CPU's polling list for Profibus or Profinet. The slave is a passive element in the network, it must wait to be addressed by the master before it reacts in any way. When the slave is deactivated (by SFC 12) the master overlooks it in the polling list; the master registers no error on a non-responding slave since it is deactivated, and the slave does not indicate an error, since it sees no request from a master on the bus.

While the slave is deactivated, the I/O areas reserved for its data exchanges with the master will not be modified If it is essential for you to know that, use the  an alarm bit  in SFC 12 D_ACT_DP telling you that the slave is deactivated, as long as D_ACT_DP is active.

Hope this helps,

Daniel Chartier