DATUM ELECTRONICS
M425 TORQUE TRANSDUCER HANDBOOK
11
DATA OUTPUT
Data output from the Datum M425 series is available
is either readable ASCII or Hex formats. This allows
a wide range of interface options using either
the Datum Interfaces or Software or even simple
terminal programs to read the data.
THE M425 TRANSDUCER HAS
THREE OPERATIONAL MODES:
MODE 1:
In this mode the Transducer will transmit Zeroed
data in the format of the $ZR strings below.
$ZR,0.0002,0.0002,0.0002,0.0002,0.0002,0.44,CS
The number of torque values per second
(resolution) can be varied by setting the baud rate
either through the Datum PowerKit software or by
using the “baud” command if using your
own software.
MODE 2:
Mode 2 is a non-transmit mode and will only
respond to commands. Sending a “help” command
in this mode will list the commands available.
MODE 3:
This is a legacy binary mode in which the
transducer will transmit the 6-byte binary format
used in earlier Datum products and the M420.
The mode can be set using the Datum PowerKit
software or the command “mode” when using your
own software. See the following section for more
information on command options.
DATA OUTPUT FORMAT:
The Series M425 Transducer can provide data either as an
individual reading or as parts of data packets. These can
be configured using the interface software to suit most
applications.
The following two standard formats (String type A and String
type B) are provided as a guide:
String type A
$ZR,0.0492,25.6,CS
Where:
$ZR
is the string identifier,
0.0492
is the mV/V value from the sensor,
25.6
is the RPM,
CS
is the data checksum
This type of string containing multiple mV/V signal value is
used where the baud rate of the receiving device is limited
and a higher data rate is required.
String type B:
$ZR,0.0492,0.0492,0.0492,0.0492,0.0492,0.0492,0.0492,0.0492,
0.0492,0.0492,24.1, 21.6,CS
Where:
$ZR
is the string identifier,
0.0492
are the last 10 signal values in mV/V from the sensor,
25.6
is the RPM,
21.6
is the shaft temperature indication,
CS
is the data checksum.
This type of string containing multiple mV/V signal value is used
where the baud rate of the receiving device is limited and a higher
data rate is required.
RAW DATA TORQUE CALCULATION:
i.e. 1.7560 mV/V = 500Nm (see calibration certificate for this value)
the torque will be [0.0492 ÷ 1.7650 x 500] Nm = 14.00Nm.
SOFTWARE COMMANDS DIRECT
TO THE M425 STATOR:
The following commands can be used with your own software to
configure the M425 Transducer and set the data output.
“Detail”
returns the following string format:
$DT, 0.0001,-0.0015,0.0015,0.00, 21.132,
4.995,0.175,CS
The string format is made of the following
data elements:
$DT
is the identifier,
0.0001
is the zeroed strain,
-0.0015
is the raw strain mV/V,
0.00
is the RPM,
21.312
is the rotor temperature deg C,
4.995
is the rotor voltage,
0.175
is the power supply current,
CS
is the checksum.
“Baud”
sets the host baud rate and reboots the system.
“Offset”
signed offset in nV/V applied to the rotor output.
“Gain”
signed gain in pV/V/quanta.
“Mode”
1
= Normal.
2
= Command mode.
3
= Compatibility mode.
“Normal”
start Transmission of rotor data string $RZ.
“Help”
lists the commands available in this mode.
“Reset”
resets the Transducer to a default setting of
(56700 baud, 1 torque value, 1 RPM value,
128 samples per second, mode 2
[awaiting a command]).
