Hi, I am also trying to setup a Profibus link from one slave to two masters. Slave in this case is a ACS 800 drive and Masters are Siemens CPU's. One of the CPU's will have read/write link to the drive and the other CPU will only read data from the Slave. Has anyone attempted to do something like this? 

Ste39

 

mtb4outdoor

 Hi

I am dealing with the same problem in my project. could you please share the results.

Thanks

Georgio

Profibus in general is multimaster system. But only one master is able to communicate with appropriate slave. I think two masters cannot communicate with one slave (only some slaves have the posibbility to communicate with several mastesr - but only via inputs to masters).

But I think it should be possible to add one slave to two hardware configuration to profibus network (the same profibus address on each network). Than connect profibus connection (two PLC and slave). Than in one PLC deactivate slave, on the second PLC activate it. If I want to I can switch activation/deactivation - I will try this solution, it should work. I will test it also with Profibus analyser and test profibus packets on profibus networks..

Thank you.

Georgio.

 

 Hello,

have you already seen this:

Reading the input data of a DP slave configured by a different DP master

or you can take some data from slave by DP/DP Coupler 

http://support.automation.siemens.com/WW/view/en/1179382

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Split from One slave communication with two masters.

Hello,

really not sure about your reason/approach to have 2 masters to one drive but I try explain like I see this situation by myself to solve, of course with my momentary experiences.

1. it depends to ABB drive to have capability for another different DP channel, maybe I expect no possible so only one DP channel here. In other case that is possible then you need create from another Master DP connection to this different ABB module link.

2. if 2 different DP channels are no available (I expect generally) then I think with maybe this solution. One DP Master link is typical f.ex. PLC1 Master to ABB drive. Ok, this is situation that PLC1 manage work with drive (speed,...). Here comes PLC2 as another master. It can maybe only collect some required data from drive or maybe also do some intervention to drive's functionality? This is important because collect data from drive and possibly from PLC1 also can be done via DP Coupler connected between PLC1 and PLC2. You can expect some amount of data to exchange between both Masters. So after define that I/O buffer as Coupler data you can have easy data from Drive and also from PLC1, inside PLC2 and maybe after some correct data exchange and PLCs program set you can have possibility run drive from PLC2 instead of PLC1, all is what you did in PLCs code and do some exchange of control data.

There are many possibilities what you can do, all is for first think about basics about connection and what your prj requires.

Thanks for the reply Duris!

1. Only one DP channel is available
2. Project requires that PLC1 remains un-touched:
   1. No communication link between PLC1 and PLC2.
   2. Two separate links between PLC1 - ACS800 and PLC2 - ACS800
3. Is it feasible?

Duris_I

Hello,

really not sure about your reason/approach to have 2 masters to one drive but I try explain like I see this situation by myself to solve, of course with my momentary experiences.

1. it depends to ABB drive to have capability for another different DP channel, maybe I expect no possible so only one DP channel here. In other case that is possible then you need create from another Master DP connection to this different ABB module link.

2. if 2 different DP channels are no available (I expect generally) then I think with maybe this solution. One DP Master link is typical f.ex. PLC1 Master to ABB drive. Ok, this is situation that PLC1 manage work with drive (speed,...). Here comes PLC2 as another master. It can maybe only collect some required data from drive or maybe also do some intervention to drive's functionality? This is important because collect data from drive and possibly from PLC1 also can be done via DP Coupler connected between PLC1 and PLC2. You can expect some amount of data to exchange between both Masters. So after define that I/O buffer as Coupler data you can have easy data from Drive and also from PLC1, inside PLC2 and maybe after some correct data exchange and PLCs program set you can have possibility run drive from PLC2 instead of PLC1, all is what you did in PLCs code and do some exchange of control data.

There are many possibilities what you can do, all is for first think about basics about connection and what your prj requires.

Hello,

user

Thanks for the reply Duris!

1. Only one DP channel is available
2. Project requires that PLC1 remains un-touched:
   1. No communication link between PLC1 and PLC2.
   2. Two separate links between PLC1 - ACS800 and PLC2 - ACS800
3. Is it feasible?

 1. if only one channel on ABB is available how you can do 2 Masters ask for data to only one port on Slave available? Really can't imagine now. Can you pls again confirm that only one port is available on ABB? From your point 1 is really not clear to me what you report about what device/s.

2. if no comm link can be prepared between possibly existed 2 PLCs then I can't imagine next data share.

3. now I can imagine maybe use of ABB next available port or channel to PLC2 (PN or Serial RS485 for Modbus) what can be used differently to existed comm used by PLC1 with DP f.ex.

Hope some one else can share some experience or solution. Simply Coupler can be used also here but logically then interchange of data between both PLC is expected also.

1. Yes, only one profibus port available. I am using RPBA-01 card and only one such card can be mounted as far as I know. 

3. Are you thinking about RMBA-01 Modbus RTU adapter?

Duris_I

Hello,

user

Thanks for the reply Duris!

1. Only one DP channel is available
2. Project requires that PLC1 remains un-touched:
   1. No communication link between PLC1 and PLC2.
   2. Two separate links between PLC1 - ACS800 and PLC2 - ACS800
3. Is it feasible?

 1. if only one channel on ABB is available how you can do 2 Masters ask for data to only one port on Slave available? Really can't imagine now. Can you pls again confirm that only one port is available on ABB? From your point 1 is really not clear to me what you report about what device/s.

2. if no comm link can be prepared between possibly existed 2 PLCs then I can't imagine next data share.

3. now I can imagine maybe use of ABB next available port or channel to PLC2 (PN or Serial RS485 for Modbus) what can be used differently to existed comm used by PLC1 with DP f.ex.

Hope some one else can share some experience or solution. Simply Coupler can be used also here but logically then interchange of data between both PLC is expected also.

Hello,

I don't have right experience with this ABB device but think about that as I expect can be used. In case your device can hold more idepended ports (with different protocols) then it can also share data independently to each one device connected to that channel. Try look to that ABB device manual about that functionality, I think it can work in case you need access data from this one device with 2 different PLCs independently. PLC1->PB DP->ABB and PLC2->MODBUS RTU(serial) or MODBUS TCP (ETH port) or PN port, so check documentation and actual ports existed on your ABB to do options.

Hello,

again pls, it's not clear to me what reason you have to have 2 different PLCs have connections to one ABB device. If this is some drive simply only I expect that one device maybe only read data from drive and other PLC set some parameters with also reading its data but really I never saw such this situation. can you be kind explain that reason?