SCADAPack 474

[Muhemmed]

Hi Guys,

Have anybody have a chance to work with SCADAPAck 474 store and forward feature? I would like to know if I want to read a modbus register of a device and then forward it to another device e.g. PLC without processing them in the SCADAPack itself, what the configuration will be?

Especially, I would like to know what the forward station ID should be and where the data are stored in SCADAPack and if they are accessible. As such in which addresses the data will be stored in the destination PLC.

[RW_Support · Accepted solution]

Muhemmed,

The "Store and Forward" (S&F) feature is more like a Modbus router. it can not read Modbus registers from server devices but, it can route and translate Modbus messages.

From what you are describing and how I understand your question, you will want to use the Modbus Scanner in the SP474 and read the Modbus server register into an "object". This object would then need to be tied to logic and moved into another object that can also be used in a different write scanner. The reason it needs to be moved into another object as an object can only have one association source with it. In other words an object cannot be an input (on the scanner) and an output (on the scanner) at the same time.

Although the YouTube video below is regarding DNP3, part 1 shows how a Modbus Scanner read works as the presenter is setting up the "use case" for DNP3.

https://www.youtube.com/watch?v=zPT29LY4RcY

An example of S&F can be the following: A SCADA client (Geo SCADA) is connected to a S&F controller (Modbus address 2) via Ethernet (Modbus/TCP). There is another SCADAPack attached to this SCADAPack via serial radio (Such as a Trio K radio) on COM3 at Modbus address 7. The SCADA client would like to poll data from Modbus station address 7.

The S&F table would be the following. The message form the SCADA comes into the Modbus/TCP interface and gets forwarded out the serial interface.

INCOMING INTERFACE	SERVER STATION	FORWARD INTERFACE	FORWARD STATION	FORWARD IP ADDR	TIMEOUT (MS)
Modbus/TCP SERVER	7	Serial 3	7		2000

As you can see the server station is the same as the forward station. If by any chance an end user would like to translate or change the Modbus addresses they can. For example if there is already an address 7 on the main network (not on the radio), the server station attached to the S&F can can also be 7, but the message the SCADA client sends a message to would be an address not on the Ethernet network. Translation is very seldom used, but is there if needed for unique scenarios.