SolidRio

1 slave to multiple masters

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Hello everyone. I got the project where plc Q00UJCPU with the module QJ71MB91 connected to the slave device via 485 channel . This plc takes some values (like current/voltage etc). i dont have access to this plc cause he is on guarantee on another service company. So question is... How to connect to this device as a other plc FX3U via 485ADP-MB (and i think RS command) module in parralel to QPLC already working link? Is this possible without harm QPLC and all the data which he takes?

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No, not possible. One "type" of communication on the port will occupy it. Alternatively, you can add more slaves to the Modbus, but that involves the QJ71MB91.

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7 hours ago, kaare_t said:

No, not possible. One "type" of communication on the port will occupy it. Alternatively, you can add more slaves to the Modbus, but that involves the QJ71MB91.

I quite dont understand your answer. But arent there the same type of commucation on device thats i need data from? Cause and QPLC and FXPLC will use 485 interface for this. And i red something about some divices thats allow you take data from the existing link, like this:

http://www.iccdesigns.com/millennium-series/12-xltr-1000.html

http://www.miille.com/366-10p-xyz.htm

Can you give advice on this?

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You can extend your bus by multiple devices, and for example you can add a gateway like the one you have linked. But to configure these new devices/gateways you need to access the master on the bus (probably the Q-series?). So yes, it is possible, but you need to configure/program the master first. If you can change the configuration then you can change the bus.

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