Ideas in Measuring ..
TECHNIQUES LIMITED
Page 18
LDU 68 Series Manual
5.3 Calibration Commands CE, CM, DS, DP, CZ, CG, ZT, FD, CS, ZI
Note: TAC represents the Traceable Access Code (calibration counter) which
increments every time new calibration data is stored. Calibration values are only
stored in EEPROM when the CS command is issued (see CS command Page 15)
With this command you can either read the current TAC value or enable a calibration command. To
check the current TAC value issue the command without any additional parameters. To enable a
calibration command, issue the CE command with the current TAC value. See table below.
This command MUST be issued PRIOR to any attempt to change calibration parameters
such as CZ, CG etc.
In legal for trade applications the TAC value can be used to check if any
critical parameters have been changed without re-verification. After each calibration the TAC
counter increases by 1.
CE TAC counter reading
Master (PC / PLC) sends
LDU XX.X responds
Result
CE
CE_17
E+00017 (example)
OK
Current TAC value is 17
Calibration commands enabled
This command sets the maximum output value. Permitted values are between 1 and 99999.
Factory default value CM = 99999. To check the current value issue the CM command without any
additional parameters. To change the value of CM, issue the CE command with the current TAC
value and then CM and the new setting. See table below.
The value of CM will determine the point at which the output will change to “oooooo” signifying
over-range.
Please note that the Set Zero (SZ) and the automatic Zero Track (ZT) functions are limited to ± 2 %
of the CM value.
CM Set maximum output value
Master (PC / PLC) sends
LDU XX.X responds
Result
CE
CM
CM_50000
CE_17
E+00017 (example)
M+30000
OK
OK
Current TAC value is 17
Current output maximum is set to 30,000
Output maximum changed to 50,000
Calibration commands enabled
This command allows you to set different output reading step sizes. Permitted values are 1, 2, 5,
10, 20, 50, 100, and 200. Factory default value DS = 1. For example, if the step size is set to 2,
then the output value will go up or down in 2s. To check the current step size, issue the DS
command without any additional parameters. To change the value of DS, issue the CE command
with the current TAC value and then DS and the new setting. See table below.
DS Set output reading step size
Master (PC / PLC) sends
LDU XX.X responds
Result
CE
DS
DS_50
CE_17
E+00017 (example)
S+00002
OK
OK
Current TAC value is 17
Display step size is set to 2
Display step size changed to 50
Calibration commands enabled
Issue 1h
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 19
LDU 68 Series Manual
This command allows the decimal point to be positioned anywhere between the most and least
significant digits. To check the current position, issue the DP command without any additional
parameters. To change the decimal point position, issue the CE command with the current TAC
value and then DP and the new setting. See table below.
DP Set decimal point position
Master (PC / PLC) sends
LDU XX.X responds
Result
CE
DP
DP_0
CE_17
E+00017 (example)
P+00002
OK
OK
Current TAC value is 17
Decimal point is set to 2 places (xxx.xx)
Decimal point set to no places (xxxxx)
Calibration commands enabled
For the best system performance, calibrate the gain (span) as near to the display maximum (CM)
as possible. A minimum calibration load of at least 20% is recommended. Factory default
calibration gain setting 20000 counts = 2.0000 mV/V input signal. Permitted values 0 - 99999
This command sets the calibration span or gain which is a reference point for all weight
calculations (TAC protected).To check the current gain calibration value, issue the CG command
without any additional parameters. To change the calibration gain value, issue the CE command
with the current TAC value and then CG (with the equivalent load applied). See table below.
CG Set calibration gain (Span)
Master (PC / PLC) sends
LDU XX.X responds
Result
CE
CG
CG_15000
CE_17
E+00017 (example)
G+10000
OK
OK
Current TAC value is 17
Calibration gain set at 10000 counts
Calibration gain set to15000 counts
Calibration commands enabled
This command sets the calibration zero point which is a reference point for all weight calculations
(TAC protected). To set a new calibration zero, issue the CE command with the current TAC value
and then CZ (when there is no load applied). See table below. Factory default ~ 0mV/V input signal
CZ Set the calibration zero point
Master (PC / PLC) sends
LDU XX.X responds
Result
CE
E+00017 (example)
Current TAC value is 17
CE_17
OK
Calibration commands enabled
CZ
OK
New zero point saved
ZT continues over ....
Issue 1h
This command sets the zero tracking band in divisions. To check the current zero tracking band,
issue the ZT command without any additional parameters. To change the zero tracking band, issue
the CE command with the current TAC value and then ZT followed by the new setting.
ZT Zero tracking band
Master (PC / PLC) sends
LDU XX.X responds
Result
CE
ZT
ZT_2
CE_17
E+00017 (example)
Z+00001
OK
OK
Current TAC value is 17
Zero tracking band ± 1 divisions
Zero tracking band changed to ± 2 division
Calibration commands enabled
