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SmartM - Intelligent GSM/GPRS based RS485 Gateway

Manufacturer: Evelta
Part No: SmartM
Availability: Out Of Stock

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SmartM is small and reliable solution for your next IoT project. Keeping the latest trends in mind new data transfer method is introduced. Now instead of sending data to server via traditional methods like TCP/UDP, SmartM can send data directly to your HTTP server or web service and in a very friendly format known as JSON (JavaScript Object Notation). Since JSON is one of the common data exchange method available in all web technologies, so implementing a receiving frontend for SmartM will be much easier than writing a TCP listener. This will also help lower down your web server requirements and hence the overall cost of implementation.

 About JSON

JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate JSON data. JSON is a text format that is completely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. These properties make JSON an ideal data-interchange language.


The reason for introducing JSON to SmartM was to ease and expedite front end development for it. Since most of the web developers are very much familiar with formats like JSON and ample amount of support available on web. Moreover, all web development platforms support JSON and its parsing. This is the reason JSON has become common data exchange format between IoT devices and web services.


SmartM can work in two different modes of operation

A. RS485 Gateway

B. Transparent

Device can be configured to work in any mode using “appmode” command. Once configured device must reboot for mode change to take effect.

RS485 Gateway Mode:

In this mode device collects data periodically from connected slaves based on the register configuration file (reginfo) loaded in the device. Device supports a maximum of 10 slaves for a reliable operation. The transmission rate can be configured for this mode. When connecting different types of slaves, please make sure the MODBUS communication parameters are same for all the devices. E.g. user cannot connect a device that communicates at 9600 baud rate with another device running at 115200.

Please refer to section Register Information File section for more information on reginfo file format.

Transparent Mode:

In this mode of operation, device creates a transparent channel between server and external MODBUS. Anything sent from the server is passed directly without any modification over MODBUS and vice-versa. This mode is mainly useful where user need to take exclusive access of MODBUS or devices on MODBUS.

In transparent mode, device makes a TCP socket connection to server and on successful connect device sends its device ID in format “UID=”. After this any data sent to the device will be passed on to MODBUS slave and any data (raw) coming from MODBUS slave will be sent back to server.

Feature are listed below :

·              Runtime configurable register set

·              Multi slave support

·              JSON support

·              Secure data transfer via HTTPS

·              Offline data storage in case of server unavailability

·              Bluetooth support for configuration and easy installation

·              Remote configuration via SMS and server

·              OTA Upgrades

·              Expandable using LUA scripting

·              Post data processing using LUA script

·              Switch between gateway and transparent mode any time.

·              MODBUS protocol selection RTU or ASCII

Sample JSON Packet in Gateway Mode:


"uid": 222,

"info": {

"dt": 1479285763,

"txn": "E",

"msgid": 11720,

"cmdkey": "",

"cmdval": ""


"modbus": [{

"id": 1,

"data": {

"reg1": 123,

"reg2": 456,

"reg3": 789


}, {

"id": 2,

"data": {

"reg1": 123



"io": {

"gpio": 0,

"analog": 1935,

"box": 0


"pwr": {

"main": 1,

"batt": 1,

"volt": 3826


"dbg": {

"status": [5, 5, 22, 8, 3, 1],

"ver": ["1.0CHKS", “1.0”],

"lib": "4.70"



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