Communication
MODBUS Master-Slave Communication
RS232 (USB) Port – Serial COM0 All Micro PLCs have built-in the universal communication port with optional USB or RS232 interface. USB interface complies with standard functional specification of USB1.1 Besides providing the standard RS232 interface, the universal port also provided USB interface since more and more notebook computers are using USB port to replace COM ports due to light weight and thickness considerations. To connect to the RS232 port, use an RS232 cable with galvanic isolation or USB Cable to connect to USB port of PC. RS232ports are commonly used for interfacing hardwareHMI panels and other devices through Modbus RTU/ASCII communications. RS232 Port can be used as a Modbus RTU master or slave protocol device, or handle ASCII data In or Out (ASCII stands for American Standard Code for Information Interchange and defines a Modbus is the most popular industrial protocol being used today, for good reasons. It is simple, inexpensive, universal, and easy to use. The Micro PLC can be networked to other Micro PLCs, data input devices (barcode readers, weight scales, etc.), and/or data output devices (serial printers, serial text displays, etc.). It is also possible to network the Micro PLC to other 3rd party PLCs and devices that have the ability to communicate using the Modbus RTU protocol. Modbus -Compatible Rievtech Micro PLCs are compatible with the world’s Modbus* de facto standard and can serve as both Modbus master and slave RTUs, which are ideal for air conditioning or temperature control etc.
MASTER
SLAVE
Initiate Request
Perform the Action Initiate the Response
Receive the Response
The default device address is 1, but can be configured to any desired address via xlogicSoft.
* Protocol developed by Modicon Inc., an American company
MODBUS Master Command
READ DATA
WRITE DATA
01 Read Coils 0x 1x
05 Write Single Coil
02 Read Discrete Input 0x
06 Write Single Register
03 Read Holding Registers 4x
15 Write Multiple Coils
04 Read Input Registers 3x
16 Write Multiple Registers
character encoding method for text that is used in computers and other communication devices). With special accessory – PRO-RS485 Cable, the universal port can serve as RS485 Port.
RS232 Cable
USB-Cable
RS-485 PRO Cable
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