hp34970a: Add option to specify channel list and configuration

hp34970a.py

+import dataclasses
 import datetime
+import re
 import signal
 import time
 
 import click
 import serial
 
-from ptblab import datalogger, utils, win32time
+from ptblab import datalogger, utils, win32time, terminal
 
 
 class HP34970A:
@@ -104,16 +106,64 @@ class HP34970A:
         self.send(b'ABORT')
 
 
+
+UNITS = {
+    'FRES':  'Ohm',
+    'RES':   'Ohm',
+    'TEMP':  'K',
+}
+
+
+@dataclasses.dataclass
+class Channel:
+    number: int
+    func: str
+    spec: str
+    nplc: int
+    units: str
+
+    @classmethod
+    def parse(cls, s):
+        m = re.match(r'^(\d+):([A-Z]+):([^:]+):(\d+)$', s)
+        if not m:
+            raise ValueError(s)
+        return cls(int(m.group(1)), m.group(2), m.group(3), int(m.group(4)), UNITS[m.group(2)])
+
+
 @click.command()
 @click.argument('filename', required=False)
 @click.option('--device', '-d', metavar='DEV', default='COM4')
 @click.option('--datadir', type=click.Path(), help='Data folder for datalogger mode.')
 @click.option('--dataname', default='temp2', metavar='STRING', help='Data name in datalogger mode.')
+@click.option('--channel', '-c', default=('102:FRES:1000:20',), metavar='SPEC', help='Channel specification.', multiple=True)
 @utils.config_option(section='hp34970a')
-def main(filename, device, datadir, dataname):
+def main(filename, device, channel, datadir, dataname):
+    """Acquire readings from Agilent 34970A data acquisition unit.
+
+    Channel configuration is specified with the --channel option followed by a
+    string in the form N:FUNC:SPEC:NPLC where N is the channel number, FUNC is
+    the function, SPEC are furhter qualifications passed to the "CONF:FUNC"
+    SCPI command, and NPLC is the integration time in number of power line
+    cycles. See the instrument manual for details.
+
+    Channels are always read in ascending channel number.
+
+    Examples:
+
+    - 101:FRES:1000:20 : channel 101, 4-wire resistance measurement, 1000 Ohm
+    range, 20 power line cycles integration time.
+
+    - 102:TEMP:FRTD,85:10 : channel 102, 4-wire RTD measurement, calibration
+    with alpha = 0.00385, 10 power line cycles integration time.
+
+    """
 
     win32time.set_resolution(win32time.get_resolution().max)
     data = datalogger.open_data_file(datadir, dataname, filename)
+    terminal.setup()
+
+    spec = sorted((Channel.parse(c) for c in channel), key=lambda c: c.number)
+    frmt = '{:.3f}  {:s}  ' + '  '.join(f'{{:.4f}} {c.units}' for c in spec)
 
     instr = HP34970A(device)
 
@@ -130,14 +180,16 @@ def main(filename, device, datadir, dataname):
     # Wait for operation to complete.
     instr.query(b'*OPC?')
 
-    # Setup 4-wire Pt100 temperature measuremet for channel 101.
-    instr.send(b'CONF:TEMP FRTD,85,1,1E-6,(@101)')
-
-    # Set units to K.
-    instr.send(b'UNIT:TEMP K,(@101)')
+    for c in spec:
+        instr.send(f'CONF:{c.func:s} {c.spec},(@{c.number:d})'.encode('ascii'))
+        instr.send(f'SENS:{c.func:s}:NPLC {c.nplc:d},(@{c.number:d})'.encode('ascii'))
+        # Set units to K for temperature readings.
+        if c.func == 'FTEMP' or c.func == 'TEMP':
+            instr.send(f'UNIT:TEMP K,(@{c.number:d})'.encode('ascii'))
 
-    # Set integration time in units of number of power line cycles (PLCs).
-    instr.send(b'SENS:TEMP:NPLC 20,(@101)')
+    # Set scan list.
+    channels = ','.join(str(c.number) for c in spec)
+    instr.send(f'ROUTE:SCAN (@{channels})'.encode('ascii'))
 
     # Set scan interval to 1 second.
     instr.send(b'TRIG:SOURCE TIMER')
@@ -147,10 +199,11 @@ def main(filename, device, datadir, dataname):
     instr.send(b'TRIG:COUNT INFINITY')
 
     # Acquire data.
-    for timestamp, temp, v in instr.scan():
+    for timestamp, *values in instr.scan():
         t = datetime.datetime.fromtimestamp(timestamp).isoformat(' ', 'milliseconds')
-        print(f'{timestamp:.3f}  {t}  {temp:.4f} K', end='\r')
-        data.write(timestamp, temp)
+        print(frmt.format(timestamp, t, *values), end='\033[0K\r')
+        data.write(timestamp, *values)
+    print()
 
 
 if __name__ == '__main__':