Ideas in Measuring ..
TECHNIQUES LIMITED
Page 26
LDU 68 Series Manual
The checksum is derived as follows:-
a) Add together the ASCII values of all 15 characters in the string
b) Convert the decimal result to hexadecimal.
c) Remove the most significant digit from the hexadecimal result
d) Invert the remaining hexadecimal value and add 1
e) Convert the hexadecimal value to characters.
GW Get the ‘Long’ weight value (Continued)
First bitmapped binary value:
Second bitmapped binary value:
1 not used
1 Signal stable
2 not used
2 Zero action performed
4 Output 0 active
4 Tare active
8 Output 1 active
8
not used
Leading character
signifies response
to GW command
Net Weight
Excluding
Decimal point
Gross Weight
Excluding
Decimal point
First bitmapped
binary value
Second bitmapped
binary value
Checksum
W +00100 +01100 5 1 0A
Issue 1h
Please note that during the period after the measuring cycle has been triggered but before the
value of GA has been updated, the GA command will return a value 99999. See Checkweigher
commands section 5.2
Issuing the GA command, the LDU returns the current weight average calculated over the
Measuring Time MT. The GA value is only updated after another measuring cycle is completed. the
format of the response includes any decimal places etc. which may have been set.
GA Get Average
Master (PC / PLC) sends
LDU XX.X responds
Result
GA
A+01.100
Weight average (over time MT) GA = 1.100g
Page 27
LDU 68 Series Manual
Ideas in Measuring ..
TECHNIQUES LIMITED
SF Send the Filtered value continuously (Display Mode ONLY)
Master (PC / PLC) sends
LDU XX.X responds
Result
SF
F+01.000
Filtered weight value = 1.000 divisions
This command sends the filtered weight value continuously. The filtered weight value is a rolling
average of the weight readings over a time set by the FF command. This command is normally
used when the LDU is connected to an external display where a more stable result is required.
SW Send the ‘Long’ weight value continuously
This command sends the ‘long’ weight value continuously. The SW command is issued without any
parameters and the unit continually returns a string in the format
W+00100+011005109
which
contains the current net weight, the current gross weight, the status values and a checksum. The
first two sections of the returned string contains the net weight and the gross weight values
followed by two hexadecimal characters which represent two bitmapped status indicators. The last
two hexadecimal characters represent the checksum, which is the inverse of the sum of all the
ASCII values of the string, not including the checksum characters. See the GW command under
section 5.6 for further details. Please note that the decimal point information is not transmitted.
Please note that during the period after the measuring cycle has been triggered but before the
value of SA has been updated, the SA command will return a value 99999.
See the check weighing timing diagram on page 17.
This command sends the ‘average’ weight value continuously . The SA command is issued without
any parameters and the LDU returns the current weight average calculated over the Measuring
Time MT. The SA value is only updated after another measuring cycle is completed. The format of
the response includes any decimal places etc. which may have been set.
SA Send the ‘Average’ weight value continuously
Master (PC / PLC) sends
LDU XX.X responds
Result
SA
A+01.100
Weight average (over time MT) SA = 1.100g
The following commands allow the Gross, Net, Filtered, ‘Long’ and ‘Average’ weight values to be
transmitted continuously. Transmission will start as soon as the relevant command has been
received and will continue until another valid command is accepted by the LDU. The data output
rate will depend on the baud rate being used e.g. with a baud rate of 9600 approximately 100
readings per second can be transmitted.
Note : The SG, SN, SF, SW and SA commands will only work if the LDU has been set to full duplex
5.8 Auto-transmit commands SG, SN, SF, SW, SA
SG Send the Gross weight value continuously
Master (PC / PLC) sends
LDU XX.X responds
Result
SG
G+01.100
Gross weight value = 1.100 divisions
SN Send the Net weight value continuously
Master (PC / PLC) sends
LDU XX.X responds
Result
SN
N+01.000
Net weight value = 1.000 divisions
This command sends the net weight value continuously.
This command sends the gross weight value continuously.
Issue 1h
