AP513 ACROPACK
USER
’S MANUAL
Acromag, Inc. Tel: 248-295-0310
- 42 -
http://www.acromag.com
- 42 -
www.acromag.com
1
DSR - NOT SUPPORTED
2
RI - NOT SUPPORTED.
3
CD - NOT SUPPORTED
4
CTS - If the channel is in the loopback mode (MCR bit 4 = 1),
then the state of RTS# in the MCR is reflected.
5
DSR - NOT SUPPORTED
6
RI - NOT SUPPORTED
7
CD - NOT SUPPORTED
Note that reading MSR clears the delta-modem status indication (bit 0) but
has no effect on the bit-4 status bit. For both the LSR & MSR, the setting of
the status bits during a status register read operation is inhibited (the status
bit will not be set until the trailing edge of the read). However, if the same
status condition occurs during a read operation, that status bit is cleared on
the trailing edge of the read instead of being set again.
Note that not all UART signal paths are used by the AP513 models and their
corresponding UART pins are tied high (+3.3). This includes, RI (Ring
Indicator), DSR (Data Set Ready), and CD (Carrier Detect).
A power-up or system reset sets MSR bit-
0 to “0” (bit 4 is determined by the
corresponding input signal). All other bits are not used.
3.4.11 Modem Status Register (MSR)
–
Write Only
Table 3.19 Modem Status Register
MSR
Bit
FUNCTION
PROGRAMMING
0
Receiver
Disable
Modes
This is only applicable when MSR[2] = 1.
0 = All RX data and Xon/Xoff flow control
characters are ignored.
1 = All RX data is ignored. Xon/xoff flow control
characters are detected and acted upon.
1
Transmitter
Disable
Modes
This bit is only applicable when MSR[3] = 1.
0 = No Xon/Xoff software flow control characters
will be transmitted when the transmitter is
disabled. If there is a pending xon/xoff character
to be sent while the transmitter is disabled, it will
be transmitted. No additional xon/xoff
characters will be sent.