
   Communication with volt/ohm meters

=== separates different volt meter types

===
VoltCraft M-4650CR

  COMx:1200,N,7,2,RS,CD,DS,CD
  (flow control none,RTS On/Off,DTR On, all other off)

Voltmeter sends periodically (1/s):
text string 14 chars long (last char is always CR):

examples (ends at @@@):
 (@... measured property; *... scale)

123456789ABCDE

@DCV
*200mV
DC-000.26mV  CR

*2V
DC-0.0027 V  CR

*20V
DC-00.002 V  CR

*200V
DC-000.03 V  CR

*1000V
DC-0000.0 V  CR

@ACV
*750V
AC 0001.5 V  CR
*200V
AC-000.02 V  CR
*20V
AC 00.040 V  CR
*2V
AC 0.0768 V  CR
*200mV
AC 068.53mV  CR

@ACA
*2mA
AC 0.0006mA  CR
*200mA
AC 000.09mA  CR
*20A
AC 00.000 A  CR

@DCA
*20A
DC 00.003 A  CR
*200mA
DC-000.09mA  CR
*2mA
DC 0.0010mA  CR

@hFE
   0000.1    CR

@LOGIC
   READY     CR

@CX
*2000pF
   0011.4pF  CR
*200nF
  -000.05nF  CR
*20uF
  -00.013uF  CR

@fKHz
*200kHz
   000.02kHz CR
*20kHz
   00.003kHz CR

@OHM
*200Ohm
   000.38 OhmCR
*2KOhm
   0.0009kOhmCR
*20KOhm
   00.002kOhmCR
*200KOhm
   000.00kOhmCR
*2MOhm
  -0.0001MOhmCR
*20MOhm
   00.000MOhmCR

@@@

Wires:

  Voltmeter  Signal           RS232        Signal
                              9pin 25pin
    TXD      send to PC       2    3        RXD Receive data
    DTR                       4   20        DTR Data terminal ready
    RTS      standing H       7    4        RTS Request to send
    RXD      receive from PC  3    2        TXD Transmit data
    SG       signal ground    5    7        SG  Signal ground


===
METEX M3850, M3830
.. the same parameters and formats as VoltCraft

