General Standards Corporation PC104P-SIO4BX, Hardware User Manual

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PC104P-SIO4BX User Manual, Revision: 0
General Standards Corporation
8302A Whitesburg Drive Huntsville, AL 35802, Phone: (256) 880-8787
3.7 Multiprotocol Transceiver Control
The SIO4BX has multiprotocol transceivers which allow RS422/RS485, RS423, RS232, and V.35 modes. The
Mode is set by the Protocol Mode filed in the Pin Source Register.
Mode TxC RxC AuxC TxD RxD RTS CTS DCD
RS-422/RS-485 RS-422 RS-422 RS-422 RS-422 RS-422 RS-422 RS-422 RS-422
RS-423 RS-423 RS-423 High_Z RS-423 RS-423 RS-423 RS-423 High_Z
RS-232 RS-232 RS-232 RS-232 RS-232 RS-232 RS-232 RS-232 RS-232
V.35 V.35 V.35 V.35 V.35 V.35 RS-232 RS-232 V.35
3.8 DCE/DTE Mode
As all signals are bidirectional, the DCE or DTE mode will set the direction for each signal. For the transceivers to
be configured as either DTE or DCE, set the DCE/DTE Enable bit in the Pin Source register (D31). The following
table gives the input/output configuration for each signal: The DCD and AuxC direction is set in the Pin Source
register fields, independent of DCE/DTE mode.
Signal DTE DCE DTE Ext Loopback DCE Ext Loopback
TxC TxC Out RxC In TxC Out / RxC In Unused
RxC RxC In TxC Out Unused TxC Out / RxC In
TxD TxD Out RxD In TxD Out / RxD In Unused
RxD RxD In TxD Out Unused TxD Out / RxD In
RTS RTS Out CTS In RTS Out / CTS In Unused
CTS CTS In RTS Out Unused RTS Out / CTS In
DCD Direction controlled by Pin Source Reg D16:15
AuxC Direction controlled by Pin Source Reg D18:17
3.9 General Purpose IO
Unused signals at the cable may be used for general purpose IO. The Pin Source and Pin Status Registers provide
for simple IO control of all the cable interface signals. For outputs, the value is set using the appropriate field in the
Pin Source Register. All inputs can be read via the Pin Status register.
The direction of the DTE/DCE signals (RxD, TxD, RxC, TxC, CTS, RTS) will still be controlled by the DTE / DCE
mode control. For example: In DTE mode, DTE_TxC, DTE_TxD, and DTE_RTS may only be used as general
purpose outputs, and DTE_RxC, DTE_RxD, and DTE_CTS may only be used as general purpose inputs.