AP500/AP520/AP521 ACROPACK
USER
’S MANUAL
Acromag, Inc. Tel: 248-295-0310
- 38 - http://www.acromag.com
- 38 -
www.acromag.com
and Xoff2.
0011 = No transmit flow control. Receiver
compares Xon1 and Xon2, Xoff1 and Xoff2.
4
Enhanced
Function
Control
0 = Disable and latch the Enhanced Functions: the
IER bits 4-7, ISR bits 4-5, FCR bits 4-5, MCR bits
5-7. This feature prevents existing software
from altering or overwriting the enhanced
functions.
1 = Enables the enhanced functions. Allows the
IER bits 4-7, ISR bits 4-5, FCR bits 4-5, and MCR
bits
5-7 to be modified.
5
Special
Character
Detect
Control
0 = Disable special character detect.
1 = Enable special character detect. Incoming
receive characters are compared with Xoff-2
data. If a match exists, the receive data will be
transferred to FIFO and ISR bit-4 will be set to
indicate detection of special character. Bit-0 of
the Xoff/Xon registers corresponds with the
LSB bit for the receive character. When this
feature is enabled, the normal software flow
control must be disabled (EFR bits 0-3 must be
set to a logic “0”).
6
RTS
Hardware
Flow
Control
0 = Disable Automatic RTS flow control.
1= Enable Automatic RTS flow control. The RTS
pin can be automatically controlled to indicate
local buffer overflows to remote buffers.
When automatic hardware flow control is
enabled, an interrupt will be generated when
the receive FIFO is filled to the program trigger
level and RTS will go to a logic “1” at the next
trigger level. RTS will return to a logic “0”
when data is unloaded below the next lower
trigger level. RTS functions normally when
hardware flow control is disabled. FCTR bits0-
1 are used to set the RTS delay
timer/trigger level.
7
CTS
Hardware
Flow
0 = Disable Automatic CTS flow control.
1 = Enable Automatic CTS flow control.