Controlling a device that only interacts via Hyperterminal using python
I am trying to write a basic driver to control a device that only interacts with hyperterminal. All the inputs expect HT formated data and all of the returns include copious equal signs, newlines, and spaces in order to get the formatting correct for human visualization. I am pretty sure that the returns are generating trouble, as I am throwing exceptions a lot, but I am not sure how else I can handle it. Does anyone know of a better way to do this?
Device manual: http://us.startech.com/media/products/PCM815SHNA/Manuals/PCM815SHNA.pdf
import visa
import re
class iopower8(visa.SerialInstrument):
#initialization
def __init__(self,loc):
visa.SerialInstrument.__init__(self,loc)
self.term_chars = '\r' #set terminal characters
self.write('\r\r') #start faux 'Hyperterminal'
def on(self, bank, out):
self.ask("on " + str(bank) + " " + str(out))
for i in range (1,3):#read buffer into void to prevent issues
try:
self.read_raw()
except(visa_exceptions.VisaIOError):
self.buffer_clear()
break
return self.status(bank, out)
def off(self, bank, out):
self.ask("of " + str(bank) + " " + str(out))
for i in range (1,3):#read buffer into void to prevent issues
try:
self.read_raw()
except(visa_exceptions.VisaIOError):
self.buffer_clear()
break
return self.status(bank, out)
def status(self, bank, port): #enter bank and port # you want to check
self.ask("st " + str(bank))
result = 'Error' #send error message regardless
for i in range (1,13):#all 12 lines need to be read out of the buffer to prevent issues later
try:
stuff = self.read()#read the line to a holding srting, and dump in void if wriong line to clear buffer
if stuff.strip() == ('='*44):
break
except(visa_exceptions.VisaIOError):
break
for i in range(1,9):
try:
stuff = self.read()#read the line to a holding string, and dump in void if wriong line to clear buffer.
if i == port: #this offset will get you to the line with the relevant port's status
result = re.match('(.*?)(ON|OFF)', stuff) #regex to the find the on/off status
#convert to boolean
if result.group(2) == 'ON':
result = True
elif result.group(2) =='OFF':
result = False
else:
result = 'ERROR'
except(visa_exceptions.VisaIOError):
self.buffer_clear()
break
return result
def buffer_clear(self): #in case of buffer jamming
while True:
try:
self.read_raw()
except(visa_exceptio开发者_如何学JAVAns.VisaIOError):
break
def all_on(self, bank):
self.ask("on " + str(bank) + " 0")
for i in range (1,3):#read buffer into void to prevent issues
try:
hold = self.read_raw()
except(visa_exceptions.VisaIOError):
self.buffer_clear()
break
def all_off(self, bank):
self.ask("of " + str(bank) + " 0")
for i in range (1,3):#read buffer into void to prevent issues
try:
self.read_raw()
except(visa_exceptions.VisaIOError):
self.buffer_clear()
break
There's nothing special about HiperTerminal. The end of line character is usually '\r\n'
or '\n'
alone.
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