Tektronix 2221 - Page 89

П
Options
and
Accessories
-
2221
Operators
Table
7-11
RS - 232 -
C
PARAMETERS
Switch
Table
7-12
Baud
Rate
C
Switch
Position
Baud
Rate
Switch
Section
Switch
Position
Function
4 3 2 1
1
Baud
ratea
2
--
Baud
ratea
0000
0001
0010
1 1
50
75
110
134.5
3
Baud
ratea
4
Baud
ratea
5
Parity enable / disable
Parity is not
checked . The
data
word is 8
bits
long .
1
Parity is
checked according
to the settings of switches 6
and 7.
A
parity
error
causes
a status byte to be sent if
RQS
is
on , The
data
word is
7 bits long with the 8th bit
being the parity
bit .
Parity
selecto
Parity
select
0100
1 1
110
1 1 1
1
000
1001
1010
1 11
1100
1 1 1
1
1 1
1 1 1 1
150
300
600
1200
1800
2000
2400
3600
4800
7200
9600
Off Line
6
7
8
Line
terminator
selection
Lines are
terminated
with
carriage return ( CR ) .
1
Lines are
terminated
with
carriage
return
- line
feed
( CR - LF ) .
9
Printer
/
Plotter selection
Section 5 of the
PARAMETERS
Switch
determines
whether or not
received
parity
errors will
cause
an
error
report ( see
Table 7-11
) . With
parity
enabled
,
seven bits
represent the characters being sent . The eighth bit is the
parity bit ,
and is
interpreted as
selected
by the
settings
of
switches 6 and 7.
These
sections
of
the
PARAMETERS
switch
determine the
parity
used
when
transmitting
and
receiving data over the RS - 232 - C interface . ODD , EVEN ,
MARK , or
SPACE
parity
is
selectable ( see
Table
7-13
) .
10
п
П
П
П
П
no
П
П
П
П
П
i
1
П
П
Printer / Plotter selection
* See Table 7-12 .
bSee
Table
7-13
.
CSwitches
9
and 10
select
printer
/
plotter
devices at
power up .
The
devices
may
be
changed
after
power - up
using
Option
commands
, or in
the case of the
2230 , the MENU
controls . Two
EPSON
formats are
selectable
.
EPS7
uses
seven
print wires
per head pass
, and is usually
slower . It is
the chr $ ( 27 ) " L "
mode
.
EPS8
uses
eight
print
wires
per
head
pass
,
and
is
usu
ally the
faster print -
head speed . It
is the chr $ (
27 ) " Y " mode
. In
this mode ,
most
Epson
and
Epson
-
compatible
printers will not
strike
any
print wire
more often
than every
second pixel . EPS8
is
selected
when parity is
disabled .
Printing
/
plotting
devices
are
selected with
the
following
switch
positions :
By setting both the transmitting and receiving devices
to use parity , some degree of checking may be done on
7 - bit data .
Setting parity to "
even " causes the
transmitter
to send a parity bit that makes the number of " mark " bits
in the
data ( plus the
parity
bit ) come
out to an
even
number
.
Upon
receiving the data ,
the
receiving device
adds up
the " mark
" bits in
the data
byte . If
an error is
detected , a system event status byte is sent . When the
event code
byte is
interpreted
, the
controller
may
make a
hardware change or alter its
routine to handle
the error .
Switch
9
Switch 10
Device
Selected
1
HP -
GL®
plotter
Epsono
(
EPS7
or
EPS8
)
ThinkJet®
printer
X - Y
Plotter
1
1
1
" Odd " parity
works in
the same way
,
except that the
number of “
mark
"
bits is
expected to be
odd .
Parity
may
also be set
to mark "
or " space ”
where the
parity bit is
always
set
to a mark
or a
space
respectively .
HP - GL
and
ThinkJet are
trademarks of
Hewlett
-
Packard
Company
.
Epson®
is a
trademark
of
Epson
Corporation .
O
7-13