• This gateway can read Modbus data from your Modbus TCP devices and publish it as SNMP data.
• It can also write to the Modbus TCP devices.
• This gateway can also do the reverse, read SNMP data and publish it as Modbus TCP data.
• It can also write to the SNMP devices.

In summary, this gateway can act as:

Master on the Modbus TCP network: Hence it is capable of reading data from the various Modbus slave devices and writing data to them if required.

Slave on the Modbus TCP network: You can use the gateway in this mode if you have a Modbus TCP master on the network which would be reading data from the gateway.

Client/Master on the SNMP network: Hence it is capable of reading data from the various SNMP devices and writing data to them if required.

Server/Slave on the SNMP network: The gateway can be configured to be a server of data values, hence another SNMP client can read data from the gateway and write data into the gateway.

Block Diagram

1)      On a site you have several UPS Systems that can provide data output on Modbus TCP.

2)      The site has a network management system on SNMP that needs the status information for the UPS systems.

3)      Since the UPS Systems  provide data output on Modbus TCP and the Network management system understands only SNMP a direct data exchange is not possible.

Block Diagram

Solution:

Solution

The devices can not directly communicate with each other as they are not on the same protocol. Modbus TCP and SNMP are Ethernet based Protocols. You need something that will convert data from SNMP device to Modbus TCP and vice versa.

ProtoConvert’s Modbus TCP to SNMP converter will be an excellent solution for this requirement. The gateway reads data from the UPS systems on Modbus TCP. It caches this data internally and then provides it on SNMP when requested from the Network Management system.

1) On the other site we have UPS and PAC units that can provide data output on SNMP.

2) The site has a SCADA on Modbus TCP that needs the status information from the PAC units and SCADA.

3)  Since the UPS and PAC provide data output on SNMP and the SCADA understands only Modbus TCP a direct data exchange is not possible.

Block Diagram

Solution

The devices can not directly communicate with each other as they are not on the same protocol. Modbus TCP and SNMP are Ethernet based Protocols. You need something that will convert data from SNMP device to Modbus TCP and vice versa.

ProtoConvert’s Modbus TCP to SNMP converter will be an excellent solution for this requirement. The gateway reads data from the SNMP devices. It caches this data internally and then provides it on Modbus TCP when requested from the SCADA.

ModbusTCP 

ModbusTCP covers the use of Modbus communication via an 'Intranet' or 'Internet' environment using the TCP/IP protocols. The most common use of the protocols at this time is for Ethernet attachment of PLC's, I/O modules, and Gateways to other simple field buses or I/O networks. There will always be this question why the connection-oriented TCP/IP protocol is used rather than the datagram-oriented UDP. The Primary reason is to keep control of an individual ‘communication’ by isolating it in a connection which can be identified, cancelled , and supervised without the need of specific action on the client and server applications. This gives the mechanism a tolerance to network performance changes, and also gives a scope to add security features such as firewalls and proxies. MODBUS/TCP/IP handles two different situations. A connection can be recognized too easily at the protocol level. A single connection can be used to carry out multiple independent communications. To add to it, TCP/IP allows a huge number of concurrent connections, so the user decides to re-use an old connection or reconnect to a frequently used connection.The Modbus device can be connected using an Ethernet port on the gateway. We can make a query using any standard Modbus Scanner to extract the value from a Modbus device. All requests are sent via TCP/IP on registered port 502.

SNMP:

Simple Network Management Protocol (SNMP) was originally made for the management of devices such as switches and routers, its usage has grown so much nowadays that it is used for monitoring of nearly any electronic device one can think of.  It is a protocol which is majorly designed to manage networked devices from a single-central location. SNMP is now used to monitor and manage television broadcast studios, airborne military platforms, automated fare collection systems, emergency radio networks, energy distribution systems, and much more.  Microsoft Windows Server 2003 provides SNMP agent software that works with third-party SNMP management software to monitor the status of managed devices and applications.