GSM/GPRS Terminal provided with this manual is a general purpose intelligent device for acquiring data from Modbus client devices and pushing the same to server on HTTP Protocol. The Terminal has a RS485 port to which maximum of 32 Modbus client devices can be connected parallel.
The Terminal can be configured to query these client devices and push the data to a centralized server.
Modbus master commands can be configured by giving the details like client ID, function code, start register and end register.
Total number of clients, Communication interval, timeout, number of poll attempts etc also can be configured.
Similarly Parameters like HTTP url, GPRS APN, user name and password can also be configured. All these configurations can be done using the configuration software provided. Once the configurations are made the terminal will be ready to use. An active GPRS enable SIM card is to be inserted in the slot provided in the terminal before using the terminal.
Proper GSM antenna also needs to be connected to the terminal. Once configurations made, SIM card inserted, Antenna connected and the terminal is powered on the terminal will works as follows.
The terminal will start polling all the configured devices at on the interval specified by the 'Communication Interval'. If the polling is failed the terminal will attempt again and the maximum number of retries will be limited to the 'Number poll Attempts' configured.
Once the poll is successful the terminal will immediately send the data to the server using HTTP post method
The data will be an ASCII string which is exactly same as the data received from the client device on sending the configured command. After this the terminal will poll the next device and communicate the data to the server. This process will continue for all the configured devices. It may be noted that the time required to poll one device will depend on following factors,