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
|
#!/usr/bin/env python
"""Epics Support for
Stanford Research Systems 570 current amplifier
"""
from .. import Device
VALID_STEPS = [1, 2, 5, 10, 20, 50, 100, 200, 500]
VALID_UNITS = ['pA/V', 'nA/V','uA/V', 'mA/V']
class SRS570(Device):
"""
SRS (Stanford Research Systems) 570 current amplifier
"""
attrs = ('sens_num', 'sens_unit', 'offset_num', 'offset_unit',
'offset_sign', 'offset_on', 'off_u_put', 'bias_put',
'gain_mode', 'filter_type', 'invert_on', 'init.PROC')
_nonpvs = ('_prefix', '_pvs', '_delim', '_nchan', '_chans')
def __init__(self, prefix):
Device.__init__(self, prefix, delim='',
attrs=self.attrs, mutable=False)
self.initialize()
def initialize(self, bias=0, gain_mode=0, filter_type=0,
invert=False):
"""set initial values"""
inv_val = 0
if invert: inv_val = 1
self.put('gain_mode', gain_mode) # 0 = low noise
self.put('filter_type', filter_type) # 0 no filter
self.put('invert_on', inv_val)
self.put('bias_put', bias)
def set_sensitivity(self, value, units, offset=None,
scale_offset=True):
"set sensitivity"
if value not in VALID_STEPS or units not in VALID_UNITS:
print('invalid input')
return
ival = VALID_STEPS.index(value)
uval = VALID_UNITS.index(units)
self.put('sens_num', ival)
self.put('sens_unit', uval)
if scale_offset:
# scale offset to by 0.1 x sensitivity
# i.e, a sensitivity of 200 nA/V should
# set set the input offset to 20 nA.
ioff = ival - 3
uoff = uval
if ioff < 0:
ioff = ival + 6
uoff = uval - 1
self.put('offset_num', ioff)
self.put('offset_unit', uoff)
if offset is not None:
self.set_offset(offset)
self.put('init.PROC', 1)
def set_offset(self, value):
self.put('off_u_put', value)
def increase_sensitivity(self):
"increase sensitivity by 1 step"
snum = self.get('sens_num')
sunit = self.get('sens_unit')
if snum == 0:
snum = 9
sunit = sunit - 1
if sunit < 0:
# was at highest sensitivity
snum, sunit = 1, 0
snum = snum - 1
self.set_sensitivity(VALID_STEPS[snum], VALID_UNITS[sunit])
def decrease_sensitivity(self):
"decrease sensitivity by 1 step"
snum = self.get('sens_num')
sunit = self.get('sens_unit')
if snum == 8:
snum = -1
sunit = sunit + 1
if sunit > 3:
# was at lowest sensitivity
snum, sunit = 7, 3
snum = snum + 1
self.set_sensitivity(VALID_STEPS[snum], VALID_UNITS[sunit])
|
