Dear Ribbie,

Is the update time the only concern you have?

What about message bufferingin case of no connection to the central CPU?

Time stamping of massages in the RTU?

I would choosea telecontrol protocol (i.e ST7, DNP3, IEC 60870-5..) but not Modbus.

Maybe the SCADA does already support ony of the above protocols, then you might even not need the S7-1500 and can connect the RTU's direct to the SCADA.

Best Regards.

Dear TIBI68,

· Is the update time the only concern you have?
Yes it's the only concern I have

· What about message bufferingin case of no connection to the central CPU?
Isn't really an issue

· Time stamping of massages in the RTU?
Is nice but not necessary

· I would choosea telecontrol protocol (i.e ST7, DNP3, IEC 60870-5..) but not Modbus.
Do you have a explanation why not to choose for modbus?
Which of the above protocols do you prefer and why?

· Maybe the SCADA does already support ony of the above protocols, then you might even not needthe S7-1500 and can connect the RTU's direct to the SCADA.
The SCADA system doesn't support S7 connection, ST7, DNP3 or IEC. So this part of the connection must be an company independent protocol.

Best Regards.

Dear Ribbie,

· Is the update time the only concern you have?
Yes it's the only concern I have

Thats why I was asking. We don't know about the requirements of your application.

· What about message bufferingin case of no connection to the central CPU?
Isn't really an issue

· Time stamping of massages in the RTU?
Is nice but not necessary

These points are pending on the systems requirements.

· I would choosea telecontrol protocol (i.e ST7, DNP3, IEC 60870-5..) but not Modbus.
Do you have a explanation why not to choose for modbus?
Which of the above protocols do you prefer and why?

Telecontrol protocols are designed to handle hundreds of connections to RTU's and can povidetransmission mechanism like EDC (event driven communication) to reduce the traffic on the network to achievefast update cycles. Modbus does not have this feature.

· Maybe the SCADA does already support ony of the above protocols, then you might even not needthe S7-1500 and can connect the RTU's direct to the SCADA.
The SCADA system doesn't support S7 connection, ST7, DNP3 or IEC. So this part of the connection must be an company independent protocol.

DNP3 and IEC are company independent protocols andsupported by many othervendors. Some are even supporting ST7.

What SCADA do you have?

Best Regards.