Trying to setup a Profibus link from one slave to two masters

Hi, I am 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?
 
Like all RS-485 master/slave protocols, you can only have one master on a PROFIBUS network. Unless someone has created a device that can be used as a PROFIBUS sniffer, you'll have to think of another way to achieve your goal.

For example, if your Siemens CPU's have other communication ports besides PROFIBUS (RS-485, RS-232, Ethernet, etc.) you may be able to connect one Siemens CPU to the ACS 800 using PROFIBUS and connect the other Siemens CPU directly to the first Siemens CPU using a different protocol, such as Modbus, and read the ACS 800's data from the Siemens CPU instead of directly from the ACS 800.
 
Like all RS-485 master/slave protocols, you can only have one master on a PROFIBUS network. Unless someone has created a device that can be used as a PROFIBUS sniffer, you'll have to think of another way to achieve your goal.

For example, if your Siemens CPU's have other communication ports besides PROFIBUS (RS-485, RS-232, Ethernet, etc.) you may be able to connect one Siemens CPU to the ACS 800 using PROFIBUS and connect the other Siemens CPU directly to the first Siemens CPU using a different protocol, such as Modbus, and read the ACS 800's data from the Siemens CPU instead of directly from the ACS 800.
Thanks for the reply! Yes, routing signals through one of Siemens CPU is a possibility but some interface changes needs to be done in both the CPUs for this to work and hence not the favored option. Any other options you can think of? Do you know if there is any ABB forum where I can discuss this issue?
 
It's not super helpful to you here, but I do remember at a previous employer we had 4 machines controlled by S7-400s. Each had slave devices on Profibus and there was also a Profibus network that connected them together. I don't remember the details. It may be that the CPUs had 2 channels (like some of the S7-300s) and handled their I/O on one channel and exchanging data on the other. But...and my memory may be faulty...I remember them all being on the same Profibus network because their slave devices had to have unique node addresses. I could be totally wrong about that, though. That plant shut down in 2009....
 
It appears that the ACS800 requires the RPBA-01 PROFIBUS DP adapter module for PROFIBUS communications. If the ACS800 had multiple option module slots that could accommodate the RPBA-01, you could use two RPBA-01 adapters on a single ACS800. Unfortunately though, the ACS800 hardware manual seems to indicate there is only one option module slot that can accommodate the RPBA-01. However, the ACS800 firmware manual has a section on page 192 detailing redundant fieldbus control which makes it seem that the ACS800 can have one RPBA-01 PROFIBUS adapter and one RMBA-01 Modbus RTU adapter simultaneously. If you must use PROFIBUS to your PLC instead of Modbus RTU, you can always use a gateway such as ICC's PBDP-1000:
http://www.iccdesigns.com/millennium-series/11-pbdp-1000.html

As an alternative, you could use a single RMBA-01 Modbus RTU adapter in the ACS800 and use two PBDP-1000's to achieve what you want. The PBDP-1000 supports a Modbus RTU Sniffer driver that allows passively reading data from a slave on an existing Modbus RTU network. One PBDP-1000 would be configured as a Modbus RTU Master to read/write data on the ACS800. The other PBDP-1000 would be configured as a Modbus RTU Sniffer to sniff data exchanged between the first PBDP-1000 and the ACS800.
 
It appears that the ACS800 requires the RPBA-01 PROFIBUS DP adapter module for PROFIBUS communications. If the ACS800 had multiple option module slots that could accommodate the RPBA-01, you could use two RPBA-01 adapters on a single ACS800. Unfortunately though, the ACS800 hardware manual seems to indicate there is only one option module slot that can accommodate the RPBA-01. However, the ACS800 firmware manual has a section on page 192 detailing redundant fieldbus control which makes it seem that the ACS800 can have one RPBA-01 PROFIBUS adapter and one RMBA-01 Modbus RTU adapter simultaneously. If you must use PROFIBUS to your PLC instead of Modbus RTU, you can always use a gateway such as ICC's PBDP-1000:
http://www.iccdesigns.com/millennium-series/11-pbdp-1000.html

As an alternative, you could use a single RMBA-01 Modbus RTU adapter in the ACS800 and use two PBDP-1000's to achieve what you want. The PBDP-1000 supports a Modbus RTU Sniffer driver that allows passively reading data from a slave on an existing Modbus RTU network. One PBDP-1000 would be configured as a Modbus RTU Master to read/write data on the ACS800. The other PBDP-1000 would be configured as a Modbus RTU Sniffer to sniff data exchanged between the first PBDP-1000 and the ACS800.
Thanks for the reply! I will check this out.
 
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