UART – UART communication block

Block SymbolLicensing group: STANDARD
PIC

Function Description
The UART block allows you to read and write data via the Universal Asynchronous Receiver-Transmitter. The port parameter specifies device name. There it is possible to use two name types:

  • the address of the physical device – Usually /dev/ttyS* for Linux target or COM* for Windows. Replace "*" symbol according to the chosen serial port!
  • the virtual address – REXYGEN enables the creation of a virtual UART with which you can communicate inside REXYGEN with other blocks supporting UART such as REXLANG, PYTHON, another UART block or Modbus driver. On Linux devices, the virtual port is marked with the prefix pty: (pseudo terminal) and it is possible to connect to it from another application running on the device. On Windows devices, it is possible to use the prefix vcom, which enables communication within REXYGEN. Virtual port examples: pty:/tmp/vslave, vcom:vmaster.

UART communication has several general properties that are set using parameters such as baudrate, parity, databits and stopbits. Each packet that is received or transmitted is assigned a unique ID. The ID of the next packet is always one higher than the ID of the previous packet. Once the maximum ID is reached, the next ID assigned will be 0. The maximum ID value is determined by the maxId parameter. Data is sent with the rising edge of the idTx input.

Inputs

dataTx

Vector reference to transmitted data

Reference

lenTx

Transmitted data length (0 = whole vector)   0

Long (I32)

idTx

ID of the transmitted data packet   0

Long (I32)

idRxAck

ID of the last processed received data packet   0

Long (I32)

WAIT

Transmission suspended flag (data is buffered)

Bool

on ...

The transmitted data is still in the buffer

off ..

The transmitted data (the entire buffer) is sent

R1

Block reset

Bool

Outputs

dataRx

Vector reference to received data

Reference

lenRx

Received data length   0

Long (I32)

idRx

ID of the received data packet   0

Long (I32)

idTxAck

ID of the last processed transmitted data packet   0

Long (I32)

MORE

Additional data in the receive buffer flag

Bool

status

Internal status indicator

Long (I32)

0 ....

No Error

1 ....

Transmit buffer overflow

2 ....

Transmit data error

256 ..

Received data error

-1 ...

Failed to open port

Parameters

port

Communication device name

String

baudrate

Baudrate [bis/s] (0 = not set)   0  4000000

Long (I32)

parity

Parity

Long (I32)

0 ....

Not set

1 ....

No parity

2 ....

Odd parity

3 ....

Even parity

databits

Number of data bits (0 = not set)   0  3

Long (I32)

stopbits

Number of stop bits (0 = not set)   0  2

Long (I32)

maxId

Max value used as ID of a packet   2  10000000 4

Long (I32)

maxLen

Maximum length of the received data   1  10000000 64

Long (I32)

nmax

Allocated size of array   8  10000000 256

Long (I32)

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