159 Programmable Hardware Manual (PHM)
© Tibbo Technology Inc.
The RS485 mode is half-duplex, which means that only the transmission or reception
can occur at any given time. In this mode, the RTS line is used for direction control,
which is handled by the EM1000 automatically. The RTS line should be LOW for data
input, and HIGH for data output. This is achieved by setting the ser.dircontrol= 0-
PL_SER_DCP_LOWFORINPUT.
Do not forget that all lines of the EM1000 are configured as inputs by default. Any
line that should work as an output must be configured as such. This is done through
the io.enabled property of the i/o object. The only exceptions are the TX and RX
lines. The TX line automatically becomes an output, and the RX line automatically
becomes an output once the serial port is enabled (ser.enabled= 1- YES).
The HD/FD and RS_MODE lines have pull-up and pull-down resistors respectively. On
startup the HD/FD line defaults to HIGH (full-duplex mode), and the RS_MODE line
defaults to LOW (RS232 mode).
Serial port 1
*IB1002 and IB1003 boards only
Serial port 2
*IB1002 and IB1003 boards only
Serial port 3
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