Seco SBC-C90 User Manual page 37

3.3.13 COM Port Header
Dual RS-232/RS-422/RS-485 pin header- CN29
Pin Signal RS-232 mode
1 COM1_RxD COM1_Rx+
2 COM2_RxD COM2_Rx+
3 COM1_TxD COM1_Tx-
4 COM2_TxD COM2_Tx-
5 GND GND
7 COM1_RTS# COM1_Tx+
8 COM2_RTS# COM2_Tx+
9 COM1_CTS# COM1_Rx-
10 COM2_CTS# COM2_Rx-
Signals Description
COM1_RxD/COM2_RxD: COM port #1 / #2 RS-232 Receive data
COM1_TxD/COM2_TxD: COM port #1 / #2x RS-232 Transmit data
COM1_RTS#/COM2_RTS#: COM port #1 / #2 RS-232 Request to Send handshaking signal.
COM1_CTS#/COM2_CTS#: COM port #1 / #2x RS-232 Clear To Send handshaking signal
COM1_RX+/COM1_RX-: COM port #1 RS-422 receive differential pair
COM1_TX+/COM1_TX-: COM port #1 RS-422 Transmit differential pair
COM2_RX+/COM2_RX-: COM port #2 Full Duplex RS-485 (RS-422) Receive differential pair
COM2_TX+/COM2_TX-: COM port #2 Full Duplex RS-485 (RS-422) Transmit differential pair
COM1_Data+/COM1_Data-: COM Port #1 Half Duplex RS-485 Differential Pair
COM2_Data+/COM2_Data-: COM Port #2 Half Duplex RS-485 Differential Pair
SBC-C90
SBC-C90 User Manual - Rev. First Edition: 1.0 - Last Edition: 1.0 - Author: A.R. - Reviewed by C.M. Copyright © 2021 SECO S.p.A.
Signal RS-422 mode Signal RS-485 mode
COM1_Data-
COM2_Data-
GND
COM1_Data+
COM2_Data+
The embedded controller of SBC-C90 board manages two 4-wire legacy
UARTs, which are carried to as many multistandard RS-232/RS-422/RS-
485 transceivers, allowing the implementation of two multistandard serial
ports (from now on respectively named COM1 and COM2).
These ports are available on dedicated connector CN29, which
is an internal 9-pin standard male pin header, p 2.54 mm, 5+4
pin, h = 6mm, type NELTRON p/n 2213S-10G-E06 or equivalent.
The selection of the kind of interface (RS-232, RS-422 or RS-485) can be
made via BIOS.
Please be aware that for proper RS-485 working, the RTS# signals must be
used as a handshaking signal, i.e. it is used to control the data flow direction.
When RTS# signal is driven low, then the RS-485 port is in receiving mode,
when RTS# signal is driven high then the RS-458 port is in transmitting
mode.
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