Jump to content

MODBUS 485 / MASTER to (MASTER to SLAVEs)


DC Joe

Recommended Posts

Dear All,

 

I am working on a project where I have UnilogicUnistream MASTER which read/write data from 10 slaves over CPU's 485 port.

I know that Unistream OPLC can be and MASTER and SLAVE at the same time, but I am wondering is this possible over the same 485 communication port?

 

Example: SCADA is MASTER to OPLC, and OPLC is MASTER to 10 slaves

Example: SCADA(M) --- OPLC(S & M) --- DEVICES in the FIELD (S)

 

So please can somebody to answer me and explain a little bit?

Do I need maybe one more 485 com module?

 

Or I can do it somehow over the same com port?

 

Kind regards,

Link to comment
Share on other sites

  • 1 month later...

Hi DC Joe,

 

Yes you will need additional RS485 port.

There is no option to have 2 masters on the same BUS.

In this case you will need to add the UAC-02RSC. (This communication module has one RS232 port and one RS485 port).

You will need to use the built in RS485 port for Slave purposes and the addtional port as Master.

Are you sure that the SCADA doesnt support Etherent connection?

If yes then you can set the UniStream as Slave on the Etherent port and Master on the built in RS485 port.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...