MikroElektronika PIC Microcontrollers PIC16 Manual de usuario descargar pdf (Pagina 157)

sub procedure RS485master_write(dim byref data as byte[2],

dim datalen as byte, dim address as byte)

MCU must be initialized as Master in 485 communication. It is programmer's

responsibility to ensure (by protocol) that only one device sends data via 485 bus

at a time.

dim byref data as byte[2], dim datalen as byte

Sends number of bytes (1 < datalen <= 3) from buffer via 485.

sub procedure RS485slave_read(dim byref data as byte[5])

MCU must be initialized as Slave in 485 communication.

dim byref data as byte[5]

Only messages that appropriately address Slaves will be received. As messages are

multi-byte, this procedure must be called for each byte received (see the example

at the end of the chapter). Upon receiving a message, buffer is filled with the fol-

lowing values:

data[0..2] is data; data[3] is number of bytes received (1..3) ; data[4] is set to

255(TRUE) when message is received; data[5] is set to 255(TRUE) if an error has

occurred; rest of the buffer is undefined

Procedure automatically sets data[4] and data[5] upon every received message.

These flags need to be cleared repeatedly from the program.

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RS485master_write

Prototype:

Parameters:

Effects:

Precondition:

RS485slave_read

Prototype:

Parameters:

Effects:

Precondition:

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MikroElektronika PIC Microcontrollers PIC16 Manual de usuario Pagina 157