Modbus Device Access/Control From Both Local abnd Remote Sites

Modbus TCP Gateways provides Ethernet connectivities to the legacy Modbus serial devices such as Modbus RTU/ASCII, PLC etc. Not only does it utilize the existing infrastructure and reduce the cost in cabling and maintenance, it also allows the Modbus serial to connect to the latest Modbus TCP devices.

However, some of the legacy devices or applications such as "islands of automation" still require a local connection to the controller, such as HMI panel on the job site, for operation or monitoring purposes. A feature called "Com-port redirector" or "serial pass-through" makes this connection easier than ever over the Modbus Gateway.


COM-port Redirector / Serial Pass-Through

A serial HMI (or other device) normally connects to a PLC's serial port. Adding a Modbus Gateway leaving no place to connect the HMI. With this redirector feature, the single serial port on the PLC can be shared, through the second serial port on the Modbus Gateway, to the serial HMI. It eliminates the need to reconnect the PLC to HMI panel by unplug the cable from Modbus Gateway. It keeps the existing control unchanged and extends the control system to the Ethernet.


The Modbus Gateway does not limit the Modbus RTU/ASCII to the Ethernet network only; it also provides a simple local connectivity to the existing Modbus serial application. Do you have any Modbus applications you would like to share with us? Any questions about Modbus serial redirection? Let us know your question and concerns about the Modbus communications.

Here are the products who support Com-port.

Related Articles