User manual

ZEUS user manual
Issue E
48
COM1/2 – RS232 interface
Supported on Channel A and B of the external Quad UART, the ports are buffered to
RS232 levels with ±15kV ESD protection, and support full handshaking and modem
control signals. The maximum baud rate is 921.6 Kbaud. COM1 and COM2 ports can be
accessed using DB9 connectors J11 and J15, respectively. For pin assignment and
connector details, see J11 – Serial port – COM1
on page 75 and J15 – Serial port –
COM2
on page 78.
A factory fit option configures COM1 as TTL Level signals to interface to certain
specialized modems. Please contact Eurotech Technical Support (see page 125
) for
details.
COM3 – RS232/RS485/RS422 interface
Supported on Channel C of the external Quad UART, COM3 port can be configured by
software as RS232 or RS485/RS422.
The port is buffered to RS232 (or RS485/RS422) levels with ±15kV ESD protection.
RS232 interface supports full handshaking and modem control signals. The maximum
baud rate on this channel is 921.6 Kbaud. COM3 RS232 interface is connected to the
connector J19, and RS485/422 interface is connected to the connector J18. For pin
assignment and connector details, see J18 – Serial port (RS485/422) – COM3
on page
79
and J19 – Serial ports – COM3/4 on page 80.
Three control outputs of I
2
C GPIO expander (I
2
C address 0x21) are used to select one
of the operating modes RS232, RS485 or RS422. The selection is implemented by
using two control signals (U3_RS232EN, U3_RS422EN) to enable/disable the associated
transceivers. The control signal combinations are shown in the following table:
U3_RS232EN
(EXP1_GPIO 0)
U3_RS422EN
(EXP1_GPIO 1) Selected COM3 function
1 X RS232
0 0 RS485 Full duplex
0 1 RS422 Half duplex
U3_RS232EN and U3_RS422EN are at logic ‘1’ upon
reset.