1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
|
from qolab.hardware.basic import BasicInstrument
from qolab.hardware.multimeter import Multimeter
from pyvisa import constants as pyvisa_constants
import time
class BK_5491(Multimeter):
r"""BK 5491 multimeter
Make sure to switch off the ECHO at the multimeter communication setup.
Example
-------
>>> rm = pyvisa.ResourceManager()
>>> instr=rm.open_resource('ASRL/dev/ttyUSB0::INSTR')
>>> multimeter = BK_5491(instr)
>>> print("------ Header start -------------")
>>> print(str.join("\n", multimeter.getHeader()))
>>> print("------ Header ends -------------")
"""
def __init__(self, resource, *args, **kwds):
super().__init__(*args, **kwds)
self.resource = resource
self.config["Device model"] = "BK 5491"
self.resource.read_termination = "\r\n"
self.resource.baud_rate = 9600
self.resource.data_bits = 8
self.resource.parity = pyvisa_constants.Parity.none
self.resource.stop_bits = pyvisa_constants.StopBits.one
self.resource.timeout = 5000
self.read = self.resource.read
# we need to work around the prompts which BK_5491 sends during
# communication to mimic SCPI
# if you need raw connection use self.resource.write or self.resource.query
# self.write = self.resource.write
# self.query = self.resource.query
self.read_bytes = self.resource.read_bytes
self.read_binary_values = self.resource.read_binary_values
self.query_binary_values = self.resource.query_binary_values
self.switchTime = 0.5 # switch time in seconds for Function/Measurement change
self.deviceProperties.update({"Function"})
def isPrompt(self, string):
if string[1] == ">":
return True
return False
def isPromptGood(self, prompt):
if prompt[0:2] == "=>":
return True
print(f"Error detected {prompt=}")
return False
def write(self, cmd_string):
"""Write/send command to instrument"""
return self._readwrite(cmd_string, expect_reply=False, Nattemts=1)
def query(self, cmd_string):
"""Query instrument with command"""
return self._readwrite(cmd_string, expect_reply=True, Nattemts=5)
def _readwrite(self, cmd_string, expect_reply=True, Nattemts=5):
"""
Send command to instrument or query it readings (which is also a command)
BK_5491 is not a SCPI instrument, so we get some replies (prompts *>, =>, etc)
even if we just send a command not a query. So we have to work around this.
"""
self.resource.read_bytes(self.resource.bytes_in_buffer) # clear read buffer
# print(f"dbg: {cmd_string=}")
self.resource.write(cmd_string)
if expect_reply:
reply = self.resource.read() # this should be result
# print(f"dbg: {reply=}")
if self.isPrompt(reply):
prompt = reply
if prompt[0] == "@":
if Nattemts >= 2:
"""
print(
"dbg: numeric reading is not available yet"
+ ", attempt one more time"
)
"""
time.sleep(self.switchTime)
return self._readwrite(
cmd_string, expect_reply=expect_reply, Nattemts=Nattemts - 1
)
print(
f"Error: we ask {cmd_string=}"
+ f' and got prompt "{reply}" instead of result' # noqa: W503
)
return None
else:
reply = None
prompt = self.resource.read() # this should be prompt
if not self.isPromptGood(prompt):
print(f'Error: expected good prompt but got "{prompt=}"')
return reply
def getReading(self):
"""Report current measurement displayed on the first/main display"""
ret_string = self.query("R1")
# print(f'dbg: getReading received "{ret_string}"')
return float(ret_string)
"""
BK_5491 has two displays which could be set and read separately,
here we use only setting of the 1st display (prefix S1 below)
to set the measurement and read it later.
It is also possible to set range, but I prefer to leave in to
the front panel user.
If this is needed it would be followed by 3 symbols specifiers as
outline in the manual.
"""
@BasicInstrument.tsdb_append
def getVdc(self):
self.write("S10")
return self.getReading()
@BasicInstrument.tsdb_append
def getVac(self):
self.write("S11")
return self.getReading()
@BasicInstrument.tsdb_append
def getAdc(self):
self.write("S14")
return self.getReading()
@BasicInstrument.tsdb_append
def getAac(self):
self.write("S15")
return self.getReading()
@BasicInstrument.tsdb_append
def getResistance(self):
self.write("S12")
return self.getReading()
@BasicInstrument.tsdb_append
def getResistance4Wires(self):
self.write("S13")
return self.getReading()
@BasicInstrument.tsdb_append
def getDiode(self):
self.write("S16")
return self.getReading()
@BasicInstrument.tsdb_append
def getFreq(self):
self.write("S17")
return self.getReading()
"""
With BK_5491
It is possible to send "key presses" like they are coming from the front panel
K1 - Vdc
K2 - Adc
K3 - Vac
K4 - Aac
K5 - Resistance
K6 - Diode
K7 - Frequency (Hz)
K8 - Auto
K9 - Up key
K10 - Down key
K11 - MinMax key
K12 - Hold key
K13 - Local (manual does not specify, but it works this way)
K14 - Rel key
K15 - Shift key
K16 - 2nd key
K17 - Vdc and Vac keys simultaneously
K18 - Adc and Aac keys simultaneously
K19 - Shift then Up keys (increasing the intensity of the VFD display)
K20 - Shift then Down keys (decreasing the intensity of the VFD display)
"""
def toLocal(self):
self.sendCmd("K13", expect_reply=False)
def getFunction(self):
reply = self.query("R0")
"""
According to the manual:
The reply is in 10 digits in the form <h1><h2><g1><g2><v><x><f1><r1><f2><r2>
the <f1> and <f2> correspond to measurement/function of the 1st and 2nd display.
Looks like it some sort of a lie, since in our BK_5491A with firmware v1.23,3
we get back either 11 digits (if both displays are on) or 9 if only 1st display
is on.
We are concerned with 1st (primary) display
"""
if len(reply) == 9:
f1 = reply[7]
elif len(reply) == 11:
f1 = reply[7]
else:
return "Unknown"
print(f1)
if f1 == "0":
return "Vdc"
elif f1 == "1":
return "Vac"
elif f1 == "2":
return "Resistance"
elif f1 == "3":
return "Resistance4Wires"
elif f1 == "4":
return "Adc"
elif f1 == "5":
return "Aac"
elif f1 == "6":
return "Diode"
elif f1 == "7":
return "Frequency"
elif f1 == "8":
return "V(ac+dc)"
elif f1 == "9":
return "A(ac+dc)"
elif f1 == "A":
return "Continuity"
else:
return "Unknown"
if __name__ == "__main__":
import pyvisa
print("testing")
rm = pyvisa.ResourceManager()
print(rm.list_resources())
instr = rm.open_resource("ASRL/dev/ttyUSB0::INSTR")
multimeter = BK_5491(instr)
print("------ Header start -------------")
print(str.join("\n", multimeter.getHeader()))
print("------ Header ends -------------")
|
