Rs422 Port B - Micros Systems Workstation 4 LX Service Manual

WS4 Technical Overview
RS422 Port A and RS422 B
SIgnal Name
RXD4_422
RXD4
RS422 Port B (REF: AB28/ABRD36 - Sheet 16)
UART3 in U25, the SC3200 is dedicated to the RS422 Port B. Several GPIO lines
from Super IO U15 are dedicated to the control signals used by this port. It is assigned
to COM5 and the default setting of RS422(+) designates the port as the 'sender' of
data where it is used by applications such as 3700 or 9700 to drive printers with IDN
modules installed.
The Table below summarizes the transmit, receive, and control signals for RS422 Port
B.
SIgnal Name
TXD5
422_232_SEL_5
422_MODE_5
TRANSMIT_EN5
DE_5A
DE_5B
RE_5A
RE_5B
2-36
Type
I Contains serial data received on the RS422
Interface. Produced by ANDing RXD4_422#
with inverted 422_232_SEL_4 at U14-6.
I Contains serial data received from either the
RS422 or RS232 interface. Produced by
ORing RXD4_232 and RXD4_422 at U11-8.
Figure 2-20: RS422 Port A Signal Descriptions
Type
O Contains serial data to be transmitted over the
RS422-B (U6-4, U5-4) or RS232 (U7-15)
interface. Always enabled.
O When Low (0), RS422-B interface is active.
When High (1), RS232-B Interface is active.
O When High (1), RS422-B is (+) Mode (IDN).
When Low (0), RS422-B is (-) Mode (LCC).
O Used with 422_MODE_5 to generate DE_5A,
DE_5B, RE_5A, and RE_5B for controlling
RS422 Transceivers U5 and U6.
O Transmit Enable at U6-3 for RS422-B IDN
mode. Produced by ANDing TRANSMIT_EN5
with 422_MODE_5 at U13-11.
O Transmit Enable at U5-3 for RS422-B LCC
mode. Produced by ANDing TRANSMIT_EN5
with 422_MODE_5 at U1-6.
O Receive Enable at U6-2 for RS422-B IDN
mode. Produced by ANDing TRANSMIT_EN5
ANDed with RE_5B# at U13-6.
O Receive Enable at U5-2 for RS422-B LCC
mode. Produced by inverting 422_MODE_5 at
U27-4.
Description
Description
Workstation 4 and 4 LX Field Service Guide