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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
Line
Corresponding EM1000 I/O
IC1000 cable line
RX (input)
GPIO8/RX0
17
TX (output)
GPIO9/TX0
19
CTS (input)
GPIO16/CTS0
33
RTS (output)
GPIO0/RTS0
1
DSR (input)
GPIO20/DSR0
41
DTR (output)
GPIO4/DTR0
9
HD/FD*
GPIO32
30
RS_MODE*
GPIO33
28
*IB1002 and IB1003 boards only
Serial port 2
Line
Corresponding EM1000 I/O
IC1000 cable line
RX (input)
GPIO10/RX1
21
TX (output)
GPIO11/TX1
23
CTS (input)
GPIO17/CTS1
35
RTS (output)
GPIO1/RTS1
3
DSR (input)
GPIO21/DSR1
43
DTR (output)
GPIO5/DTR1
11
HD/FD*
GPIO34
26
RS_MODE*
GPIO35
24
*IB1002 and IB1003 boards only
Serial port 3
Line
Corresponding EM1000 I/O
IC1000 cable line
RX (input)
GPIO12/RX2
25
TX (output)
GPIO13/TX2
27
CTS (input)
GPIO18/CTS2
37
RTS (output)
GPIO2/RTS2
5
DSR (input)
GPIO22/DSR2
45