PC104P-SIO4BX User Manual, Revision: 0
General Standards Corporation
8302A Whitesburg Drive Huntsville, AL 35802, Phone: (256) 880-8787
2.1.11 Channel Pin Source: Local Offset 0x0080 / 0x0084 / 0x0088 / 0x008C
The Channel Pin Source Register configures the Output source for the Clocks, Data, RTS, and DCD outputs.
31
30
29
28
27
26
25
24
DCE/DTE
Mode Enable
Termination
Disable
Loopback
Enable
DCE/DTE
Mode
Transceiver Protocol Mode
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Loop
Int
Unused
TxD
Source
TxAuxC
Source
DCD
Source
RTS
Source
USC_DCD
Direction
USC_CTS
Direction
TxC
Source
USC_RxC
Source
USC_TxC
Source
Pin Source Register
D31
DCE/DTE Mode Enable
Setting this bit enables the DCE/DTE buffer control (D28) control and Loopback controls (D29
and D23). See Transceiver control for further information.
D30
Termination Disable
For RS422/RS485 and V.35, the RxC, RxAuxC, and RxD have built in termination at the
transceivers. These internal terminations may be disabled to allow external terminations to be
used. Setting this bit will disable the internal transceiver termination resistors.
D29
External
Loopback Mode
When DCE/DTE Mode is enabled (Bit D31=1), this bit will automatically loopback the TxC/RxC,
TxD/RxD, and RTS/CTS signals at the cable (transceivers enabled).
Notes:
The DCE/DTE mode will select the set of signals (DCE or DTE) to be looped back
D28
DCE/DTE Mode
When DCE/DTE Mode is enabled (Bit D31=1), this bit set the mode to DCE (1) or DTE (0).
DCE/DTE mode changes the direction of the signals at the IO Connector.
D27:24
Transceiver Protocol Mode
D27
D26
D25
D24
Transceiver Mode
0
0
0
0
RS-422 / RS-485
0
0
0
1
RS-423
0
0
1
0
RS-232
0
0
1
1
RESERVED
0
1
0
X
RESERVED
0
1
1
0
V.35 Mode (V.35 / RS-232)
0
1
1
1
RESERVED
1
X
X
X
RESERVED
