Ideas in Measuring ..
TECHNIQUES LIMITED
Page 22
LDU 68 Series Manual
Using the command FL, a digital filter strength can be set which will eliminate most unwanted
disturbances. Please note that these filters are positioned immediately after the A/D converter and
therefore affect all aspects of the weighing operation.
5.5 Filter setting commands - FL, FF, UR
FF Filter Factor [DISPLAY MODE ONLY]
Master (PC / PLC) sends
LDU XX.X responds
Result
FF
F+00001
Filter factor set to 1
FF_4
OK
Filter factor changed to 4
WP
OK
Write parameter to EEPROM
This command allows you to select the filter level or cut off frequency. Permitted values are
between 0 to 7. To check the current setting, issue the FL command without any additional
parameters. To change the FL setting , issue the FL command with the new setting. See table
below. To save this change to EEPROM use the WP command. Factory default FL = 3
FL Filter Level (Cut off frequency)
Master (PC / PLC) sends
LDU XX.X responds
Result
FL
F+00003
Filter level set to 3
FL_1
OK
Filter level changed to 1
WP
OK
Write parameter to EEPROM
Filter Level (FL)
Cut off frequency (Hz) 3dB
0
5
1
2
2
1
3
0.5
4
0.2
5
0.1
6
0.05
7
0.02
Filter Factor (FF)
Averaging time (Seconds)
0
0.2
1
0.4
2
0.6
3
0.8
4
1.0
5
1.2
6
1.4
7
1.6
Filter Factor (FF)
Averaging time (Seconds)
8
1.8
9
2.0
10
2.2
11
2.4
12
2.6
13
2.8
14
3.0
15
3.2
This command defines the time over which a rolling average is calculated. Permitted values are
between 0 and 15. To check the current setting, issue the FF command without any additional
parameters. To change the FF setting , issue the FF command with the new setting. See table
below. To save this change to EEPROM use the WP command. Factory default FF = 0
Issue 1h
UR Set the update rate
This command defines the number of available updates per second. Factory default UR = 2.
UR=0
1
2
80 M/s
40 M/s
27 M/s
To check the current setting issue the command without any additional parameters. To change the
setting issue the command with the additional parameter. Save changes using the WP command.
See table below.
Master (PC / PLC) sends
LDU XX.X responds
Result
UR
UR_0
U+00002
OK
Update Rate set to 27 measurements/sec
Update Rate changed to 80 meas./sec.
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 23
LDU 68 Series Manual
The following commands allow you to set and reset zero and tare values. The zero set during
calibration remains the ‘true zero’ but a new ‘current zero’ can be set using the SZ command. If the
SZ command is issued and accepted then all weight values will be based in the new ‘current zero’.
Please remember that the zero value will be subject to the Zero Tracking function if enabled.
If the weight signal is not stable (as defined by the No motion range NR and the No motion time
NT) then both the set zero (SZ) and the set tare (ST) commands will be disabled.
Also the set zero (SZ) command is not allowed if the new zero value required and the ‘calibration
zero’ differ by more than 2% of the CM value (maximum displayed value)
See chapter 8 “Legal for trade” applications
5.6 Set Zero/Tare and reset Zero/Tare commands - SZ, RZ, ST, RT
This command sets a new “current zero” which is then the basis of all weight values until further
updated by the zero tracking function, another SZ command or the “reset zero” command (RZ).
The SZ command will fail (LDU responds with ERR) if the new “current zero” is more than 2% (of
the CM value) higher or lower than the “true zero” set during calibration. The SZ command will also
fail if the weight signal is not stable, as defined by the no motion range (NR) and no motion time
(NT). If the weight signal is “stable”, the response to the IS (device status - see page 11) command
will show the “signal stable” bit active and the SZ command will be accepted (OK). If the signal
stable bit is not active, the SZ command will be rejected and the LDU will respond will ERR (error).
The SZ command is issued without any parameters and will return either the OK or ERR response.
If the SZ command is accepted, the LDU responds with OK and the”zero action performed” bit of
the device status (IS) response will be active (1).
SZ Set Zero
Master (PC / PLC) sends
LDU XX.X responds
Result
SZ
OK
New zero set
This command cancels the SZ command and the zero reading reverts to that set by the CZ
command during calibration.
The RZ command is issued without any parameters and will return either the OK or ERR response.
If the RZ command is accepted, the LDU responds with OK and the”zero action performed” bit of
the device status (IS) response (see page 11) will not be active (0).
RZ Reset Zero point
Master (PC / PLC) sends
LDU XX.X responds
Result
CZ
OK
Zero reverts to calibration zero (CZ)
Issue 1h
