Hello. My customer need to have my s7plc to work with a ABB system.

And i have installed a dpdp coupler in hardware with inputs and outputs according to a list from the customer.

1. But i do not know if i should use consistent or not ?

2. And how do i connect the program signals to the areas assigned in my DB_Sends and DB_Recive ? (Should i use SFC14,15)?

Hello Draven;

Consistent data means data that is transferred in a single block over the network, using SFC 15 and SFC 14.

I always refer to Profidrive exchanges to explain the difference between consistent and non-consistent data.A Micormaster or Masterdrive using Profibus will access 2 different data areas: One is for process information, Start, Stop, speed reference...: this is the PZD area. this data can be accessed individually by the programmer, or can be accessed consistently, it is indifferent to the drive. But when you want to access parameters of the drive (the PKW area) you must read and write a 4-word telegram as a single consistent unit; if you try sending the 4 words of the telegram individually the drive wioll reject them. For PKW transactions you must use SFC 15 and SFC 14.

The main impact on consistent data transfer is that the program must wait for the program to call the SFCs to initiate data transfers, whereas with standard addressing the Profibus cycle will transfer the data on its own independant cycle, which can be faster than the PLC scan (for smaller networks).

So if for technical or programming style reasons you need to keep your data consistent, configure the DP/DP coupler data as consistent. see the attached screenshot form the DP/DP coupler manual, showing that you can mix consistent and non-consistent data in the cpoupler configuration.

DP/DP Coupler

https://support.industry.siemens.com/cs/ww/en/view/1179382

One question: why do you ask about DP_Send and DP_Recv functions? These should be used only if you have a CP 342-5 as a Profibus master on your S7-300 rack. Is this the case?

Hope this helps,

Daniel Chartier

dchartier

Hello Draven;

Consistent data means data that is transferred in a single block over the network, using SFC 15 and SFC 14.

I always refer to Profidrive exchanges to explain the difference between consistent and non-consistent data.A Micormaster or Masterdrive using Profibus will access 2 different data areas: One is for process information, Start, Stop, speed reference...: this is the PZD area. this data can be accessed individually by the programmer, or can be accessed consistently, it is indifferent to the drive. But when you want to access parameters of the drive (the PKW area) you must read and write a 4-word telegram as a single consistent unit; if you try sending the 4 words of the telegram individually the drive wioll reject them. For PKW transactions you must use SFC 15 and SFC 14.

The main impact on consistent data transfer is that the program must wait for the program to call the SFCs to initiate data transfers, whereas with standard addressing the Profibus cycle will transfer the data on its own independant cycle, which can be faster than the PLC scan (for smaller networks).

So if for technical or programming style reasons you need to keep your data consistent, configure the DP/DP coupler data as consistent. see the attached screenshot form the DP/DP coupler manual, showing that you can mix consistent and non-consistent data in the cpoupler configuration.

DP/DP Coupler

https://support.industry.siemens.com/cs/ww/en/view/1179382

One question: why do you ask about DP_Send and DP_Recv functions? These should be used only if you have a CP 342-5 as a Profibus master on your S7-300 rack. Is this the case?

Hope this helps,

Daniel Chartier

 Thanks . This helps. But i dont mean  dp_send just DB. An ordinary DB to store send and recive signals. 

Hello Draven;

A valid question. Sorry I misunderstotod the first time.

If you use SFC 14 and SFC 15, the parameter RECORD (through a ANY pointer) will allow you to connect DB addresses directly to the sent and received data. For example:

RECORD= P#DB10.DB20.0 Byte 20

will transfer 20 bytes (10 words) of DB10 starting at byte 20.

On the other hand, if you use standard addressing, data will be sent to/from IO addresses (see the screenshot in my last post) and you will have to copy this data to/from your DB in yur program.

Hope this clears things up a bit.

Daniel Chartier

Hello

To add to the brilliant explaination bydchartier……

Here is a simple explaination to how DP-DP coupler works :

To understand the concept of DP-DP Coupler, You can Imagine it as 2 Profibus DP Slaves ( Which are Mirror Images of each other ) stuck Back to Back.

Slave-1 – Communicates with Master-1 and Whatever is written by Master-1 on its outputs is transferred to Inputs of Slave-2

Slave-2 -  Communicates with Master-2 and Whatever is written by Master-2 on its outputs is transferred to Inputs of Slave-1 .

So effectively each PLC seed only 1 slave while the 2-slaves are internally connected to each other.

Here is a FAQ that explains how Inputs / Outputs of DP-DP Coupler should be assigned :

What are the special features of input/output addressing with the DP/DP coupler?

 If the DB transfer fails you can declare a certain number of words and assign them PLC side to your DB. It is not a monstruosity, but just a quick workaround.

And in the hardware configuration you must declare SPECULAR IOs:

If for example you have 10 bytes IN and 5 Out then in the other hwcfg you must declare a slot of 5 IN and 10 OUT..

That should work instantly

Draven

Hello. My customer need to have my s7plc to work with a ABB system.

And i have installed a dpdp coupler in hardware with inputs and outputs according to a list from the customer.

1. But i do not know if i should use consistent or not ?

2. And how do i connect the program signals to the areas assigned in my DB_Sends and DB_Recive ? (Should i use SFC14,15)?