python - Can I use a parallel port for RS-232 on linux? -

-

the rs232 (db9) ports on machine full, write lcd scoreboard using parallel port. making cable correct pinout not problem. need interface device using python.

here like: api similar pyserial, can set baud rate, , send string scoreboard. scoreboard has no requirements handshake or stop-bit, , supposed auto-detect. need write device, there no need read port.

i aware of pyparallel, has used similar application? appears designed parallel (lpt) protocol. scoreboard support rs232, rs422, rs485, or 20ma current loop. have done fair bit of programming rs232 devices, technical knowledge of serial communications if limited. appreciated.

http://pythonic-wisdom.blogspot.com/2008/11/accessing-parallel-port-on-linux-from.html

in short, yes can, there limits on achievable baudrate, maximum via inb/outb, usable through python gpio module, around 300,000 operations second, @ 300kbaud if write port. using linux /dev/parport @ least twice slower.

if need 9600 baud example, quite possible achieve reliable transmission, although have prepared transmission or reception being interrupted linux scheduling or python gc.

another issue voltage levels, need -10 , +10 vdc or rs-232, , can't negative voltage parallel port, you'll have add hardware that.

perhaps might or might not able fake rs422/rs485 differential signalling setting pair of pins (high, low) , (low, high) in turns.

cannot tell current loop in practice. that's https://electronics.stackexchange.com/


Comments

Post a Comment

Popular posts from this blog

delphi - How to convert bitmaps to video? -

-
Image
my application creates images fractals , love feeling of 'flying' around fractal. once saved 2000 bitmaps file , created avi using premiere. experience rather frustrating though succeeded in creating movie. spectacular. of course want create video application. don't care niftyness of codec, compression or whatever. want have video can replay on systems. in past have tried never succeeded. triggered question alas not ffmpeg running. update i decided adapt question , put bounty it. have seen several solutions attractive (because it's simple) seems me taviwrite. tried taviwriter did not succeed. in procedure taviwriter.write; function call around line 370 avierr := avisavev(s, // pchar(filename), nil, // file handler nil, // callback nstreams, // number of streams streams, compoptions); // compress options
Read more

jasper reports - Fixed header in Excel using JasperReports -

-
how can create excel report fixed header using japserreports? mean need header fixed when scroll excel file. this possible adding couple properties in jrxml file each report. take @ advanced excel features freeze panes. if wanted freeze after first column header (down left side basically) this: <statictext> <reportelement style="sans_bold" mode="opaque" x="0" y="60" width="104" height="20" forecolor="#ffffff" backcolor="#666666"> <property name="net.sf.jasperreports.export.xls.auto.filter" value="start"/> <property name="net.sf.jasperreports.export.xls.column.width" value="110"/> <property name="net.sf.jasperreports.export.xls.freeze.column.edge" value="left"/> </reportelement> &
Read more

python - ('The SQL contains 0 parameter markers, but 50 parameters were supplied', 'HY000') or TypeError: 'tuple' object is not callable -

-
import pyodbc,nltk,array cnxn = pyodbc.connect('driver={mysql odbc 5.1 driver};server=127.0.0.1;port=3306;database=information_schema;user=root; password=1234;option=3;') cursor = cnxn.cursor() cursor.execute("use collegedatabase ;") cursor.execute("select * sampledata ; ") cnxn.commit() s=[] j=[] x=[] words = [] w = [] sfq = [] pos=[] entry in cursor: s.append(entry.injury_type),j.append(entry.injury_desc) nltk.tokenize import punktwordtokenizer nltk.corpus import stopwords tokenizer = punktwordtokenizer() english_stops = set(stopwords.words('english')) in range(0,26): # filter stop words tokenizer.tokenize(j[i]) w.append([word word in tokenizer.tokenize(j[i]) if word not in english_stops]) in range(0 , 26):#converting tokenzied text ito string sfq.append(" ".join(w[a])) replacers import regexpreplacer replacer = regexpreplacer() in range (0,26):#pos tagging replacer.repl
Read more