Serial Redundancy Switch

Many applications in Industrial PLC or SCADA communication require multiple Slave devices to be shared with 2 (two) Masters. Alternatively, Single Master wants to communicate with multiple slave devices. Serial Redundancy Switch (SRS) has been designed to cater to this specific requirement. It is Protocol independent & has different operating modes. The Serial communication parameters are field selectable using DIP switch. All ports of this product are RS485 2 Wire with built in termination resistor. This product does not act as protocol converter gateway. It acts as Hub or Splitter switch for RS485 ports.

It can enable 2 Modbus Masters talk to a common RTU or a single Modbus Master to talk to Redundant RTU’s on field. During Power On, whichever Master sends a query, is connected to the Output (Slave). Incase your Master Port fails or Cable from your Primary Master to our Port has failed then SAM senses “No Communication” between the Primary Master & the Slave & seamlessly switches communication to your Secondary Master. Time Out is selectable from 1 Sec. to 1 min. This timeout is factory set. SAM will wait upto the Time Out in order to establish other connection. Manual selection of the Primary & Secondary Master is also provided for easy diagnostics. It is expected that during the failure of Primary Master connection, your Secondary master will start sending the queries. Alternatively the Switch can also be used for communication between 2 Slaves & 1 Master. The query from a Master can be broadcasted to both the Slaves but only 1 Slave need to respond at a time. This is in cases where the Slaves are Redundant. SAM 201I has been designed to cater to the requirement of Sharing / offering Redundancy for the Serial Ports. It is Protocol independent with all the 3 Ports are RS232. All the 3 Serial ports are 3KV Optically Isolated.

Offering communication Redundancy has taken roots. There is a felt need to communicate SCADA PC / HMI / DCS etc with Redundant Controllers / PLC / RTU’s / IED devices etc. SRS has been designed to cater to this requirement of the industry. It is Protocol independent & all the 3 Ports are RS232 / RS485 / RS422 configurable.

Other Details
It can enable 2 SCADA Masters talk to a common RTU or a single SCADA master to talk to Redundant RTU’s on field. It can also be connected through a PLCC modems etc.

During Power On, whichever Master sends a query, is connected to the Output ( Slave ). Incase your Master Port fails or Cable from your Primary Master to our Port has failed then SRS senses “No Communication” between the Primary Master & the Slave & bumpless switches communication to your Secondary Master. Time Out is selectable from 1 Sec. to 9 Sec. SRS will wait upto the Time Out in order to establish other connection. Manual selection of the ports is provided for easy diagnostics.

Alternatively the Switch can also be used : 

• For communication between 2 Slaves & 1 Master. The query from a Master can be broadcasted to both the Slaves but only 1 Slave need to respond at a time. This is in cases where the Slaves cannot be multidropped.
• To create cable level redundancy for devices having only a Single Serial port.