If you connect the GRD-XF/cLAN-XF to the Exemys Telemetry Server you don't need to read this section

Remote Access to serial port in Modbus mode - MW configuration

We will now see how to configure in the MW the GRDs that we use to multiplex Modbus. In this mode of operation the MW will receive the “Modbus TCP” queries sent to the port/s of the “Modbus Server” which will resend to the GRD with the slave being queried.

The TCP port to accept the incomming queries must be configure on the MW's main screen. You can also chose here to use Modbus TCP, Modbus RTU over TCP or Modbus ASCII over TCP.

We must first have the MW connected and the GRD added as indicated in “Connection between the GRD-XF and MW”.

• Let’s look at the following example:

We have 2 Modbus (RTU) devices connected in port 485 of the GRD with GRD ID = 10 without a password.

Device 1: ID Modbus 43 (query from port 502)
Device 2: ID Modbus 66 (query from port 503)

We also have 1 Modbus (ASCII) device in port  232 of the GRD with GRD ID = 13 without password.

Device 1: ID Modbus 87 (query from port 504)

MW data: (These parameters are configured in the MW connection).

MB Port: 502
Number of ports: 3
In the MW we enter in “Configuration -> GRDs” and we edit the “Serial port mode” placing it in “Modbus”.

When you press the save button it is stored in the list of valid GRDs. The mode must be MB for it to work in this manner. The following figure shows the addition of the other GRD and in the upper part the GRD added previously.

Once both GRDs are incorporated to the list we can assign them the corresponding slaves to each one and also indicate what type of Modb us protocol will be used.

To be able to add the slaves to each GRD we have to enter the Administration screen of GRDs MB and slaves, we place the cursor on the GRD in the upper part and press the +Slaves button; a window will open as the one shown in the figure below where you enter the number of the slave connected to the GRD in its serial port and the port number of the MB server from where the query will be made to that slave.

Once the corresponding slaves and its port are entered, the Modbus protocol to be used must be selected, which could be RTU or ASCII.

As it can be seen in the previous figure the GRD 10 has 2 Modbus slaves. We also determine the communications protocol, that in this case is RTU, the Timeout of the communication and then we press the save button to store the changes. The purpose of Timeout is to prevent the system from waiting for a response for an undetermined time, this time is expressed in milliseconds, therefore, when a query is sent, this is the maximum waiting time for a response, once this time is up the systems discards all the responses from that GRD until a new query occurs.

In the same manner, the slaves are added for the following GRD, but in contrast to the previous one, this one has an ASCII communication protocol.
The communication protocol is determined by the devices connected to the GRD, this means that, the required communication protocol will depend on the device to be connected.

In this manner, the two GRDs are configured from the MW side and working according to what was established in the beginning.

To access the GRD's serial port remotely you must configure it in "Remote" mode.

2022-03-17