Master Slave

[PeterW]

There is a way to attach a file. see below message input.

 

[al_d]

I have attached both master and slave projects. I downloaded each individually in each PLC. Im not 100% sure about the I/O addresses of the slave and master and on how to switch contacts on the master to switch on outputs on the slave and vice versa.

Thanks.

 

[Gambrinus]

Data exchange isn't configured correctly. Slave doesn't know who is it's master. I want to prepare example project but I want to clear it first.

 

[PeterW]

I believe there should only be one zip file as both PLC's should be in the same project, that way the master can attach to it.

At least that is what the Siemens example shows.

The example project also shows it that way.

 

[al_d]

Apparently they can be on seperate projects as if they are in the same project the slave DP address is 2 but the slave on the master profbus node can not be configured as 2 since it is already taken.

 

[PeterW]

When I look at the properties of the slave PLC in the master hardware config DP connectio, it does not contain the full options, this I believe is because the master PLC does not know where the slave PLC is.


It looks at the other PLC's in the project and asks you which to connect to, if there's only one then you will only get one choice.

For thois reason both PLC's must be in the same project.

Open the Siemens example and see what I mean. The master is set as address 4.

 

[PeterW]

file attached with addressing modified. You had the addresses set as 0 instead of 40.

 

[Gambrinus]

al_d, I make over you project. It's only 1 project with 2 stations now.

 

[Gambrinus]

Take into account: your DI/DO module start adress is 124 both for I and Q. 40 didn't work because hardware config was incorrect and was defined at 0 in your projects. Now I changed DP IO area to 40. See OB1 of ms & sl.

 

[al_d]

Thanks PeterW and Grambrinus, I see that OB1 was changed i am still a litttle confused with the code. Can i use lad (stl) to write a simple program to switch master slave contacts simutaneously or do i have to use IB QB etc.

For example will this work

Master OB1:

A I124.0
=Q124.0

Slave OB1:

A I124.0
=Q124.0

or must i change slave I/O to say I120..

Therfore

Master OB1:

A I124.0
=Q120.0

Slave OB1:

A I120.0
=Q124.0

??

 

[Gambrinus]

Of course, you can write without IB & QB - only Ix.x and Qx.x. But your code listed above will not work if you want to switch on input on one PLC and to get reaction at output of another PLC. What you have now?
Local address starts at 124 for both PLC; DP exchange area was defined at 40.
A I124.0
=Q124.0
It switches output in accordance to input at the same PLC, not at DP partner.
A I124.0
=Q120.0
You mean slave local DI24/DO16? Master don't know this address. It's not needed for it. Master and I-slave local IO modules addressing is fully independent. Only DP exchange area integrates areas of both PLC.

 

[Gambrinus]

I have appended network 2 to ms and sl OB1. And I have changed length of DP area to 1 byte because we use IB40/QB40 only. When you turn on any input of IB124, you will get a reaction at another PLC QB124. When you turn IB125, you will get a reaction at the same PLC QB125. Try it.

 

[al_d]

Ok il try it and let you know thanks. I have made this one and changed the slave I/O to 120, but you said you dont need to do this?(the one you sent me had 125?) I have also put in more networks in OB1 M/S but not sure if this is ok.

 

[Gambrinus]

You can change slave 24DI/16DO start address to 120, of course. NW1 are correct for both PLC's. NW2 is correct too, but this means Step7 translation errors only...

Master:
A I 124.0
= Q 120.0
You toggle master's internal Q-area bit Q120.0 only. This statement doesn't affects any physical output of both PLCs. Because you haven't master's DO modules attached to this address and this address don't refer master-slave exchange area defined as IB40/QB40 for both PLCs.

Slave:
A I 120.0
= Q 124.0
The same problem.

NW1 together with HW config sends data from IB124(120) through DP exchange area (QB40) to partner. Partner reads received data and stores it in own IB40. Partner toggles own QB124(120) outputs in accordance with this data as defined in partner's OB1. Of course, master physically initiates and executes data exchange. But data flow is as described.

 

[al_d]

Could you write a program that can swich on an say I124.0 in the master that switches on Q124.0 in th slave and vice versa so it affects the PLCs physical state?

Thanks.