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Document 26-833 | Edition ENG07 │ 2018-10-18
Manual
Integrated weighing and metering system
PCD2.W7x0 and PCD3.W7x0
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Saia-Burgess Controls AG
Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
Content
0-1
0
0 Content
0 Content
0.1 Document History ........................................................................................... 0-2
0.2 Brands and trademarks .................................................................................. 0-2
1 Hardware
1.1 Features .......................................................................................................... 1-1
1.2 Operation ........................................................................................................ 1-2
1.3 Technical data ................................................................................................. 1-3
1.3.1 Wiring ........................................................................................................... 1-4
1.4 Functional description ..................................................................................... 1-4
1.5 Signal processing ............................................................................................ 1-5
2 Programming
2.1 Function boxes ................................................................................................ 2-1
2.2. Data interchange between Saia PG5® FBoxes and weighing modules .......... 2-6
2.3 Overview ......................................................................................................... 2-7
3 Conguration
4 Operationoftheweighingmodule
4.1 Commissioning .............................................................................................. 4-1
4.1.2. Scaling ......................................................................................................... 4-1
4.2 Operation ....................................................................................................... 4-1
A Appendix
A.1 Icons ............................................................................................................... 5-1
A.2 Contact ........................................................................................................... 5-2
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Saia-Burgess Controls AG
Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
Content
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0
0.1 Document History
Date Version Changes Remarks
2005-09-31 EN02 completely First Publication
2007-12-13 EN03 Chapt. Ch02
Chapt. Ch03
- Data to Scale (only W710) deleted.
- Scale with calibrated weighing cells
removed
2007-11-05 EN04 Chapt. Ch01.3 Dierent connectors for PCD1|2 and
PCD3
2009-07-02 EN05 Chapt. Ch02.1 Reset
2013-10-10 EN06 - New logo and new company name
2018-10-18 ENG07 - New phone number (2015)
0.2 Brands and trademarks
Saia PCD® and Saia PG5®
are registered trademarks of Saia-Burgess Controls AG.
Technical modications are based on the current state-of-the-art technology.
Saia-Burgess Controls AG, 2018. © All rights reserved.
Published in Switzerland
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Saia-Burgess Controls AG
Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
Hardware
1-1
1
Features
1 Hardware
1.1 Features
The weighing module provides cost-eective solutions for weighing and metering,
and optimising material ows and volumes.
The PCD2|3.W7x0 module is characterised by the following features:
● Integration: The electronic weighing apparatus is placed on a standard Saia
PCD® x module. This supports a central automation concept with end-to-end
project planning and programming.
● Flexibility: All DMS weighing cells with 4 or 6 terminals can be connected.
● Economy: The module is available with two measuring channels to connect up
to six weighing cells, and also obtainable cheaply in larger quantities with only
one channel.
● High resolution: The internal measurement resolution supports 200,000
increments.
● Extensive functionality: As well as the classical weighing and zeroing
functions, dierential measurement is also possible, i.e. measuring the change
in weight per second.
● Comprehensive diagnostics: The operating state of the scales is constantly
monitored. Wire breaks and conguration and hardware errors are reported.
Prohibited overloads are even recorded permanently.
System overview
PCDx.W720 PCDx.W710
PCDx.W720
2 weighing systems to connect
up to 6 weighing cells
PCDx.W710 (obtainable only
in specied quantities)
1 weighing system to connect
up to 4 weighing cells
(The jumpers on the terminals protect the sensitive inputs against surges when not
in use).
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Saia-Burgess Controls AG
Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
Hardware
1-2
1
Operation
1.2 Operation
The PCD2|3.W7x0 module with its associated weighing cells forms one or two
independent weighing systems with great precision and impressive functionality.
The weighing cells convert mechanical forces into electrical signals, which are
processed within the module and turned into physical units of weight.
All weighing cells based on the principle of resistance strain gauge bridges can be
connected to the weighing module. Various largely standardised force and weighing cells are available on the market for force measurements and weighing applications. With the PCD2|3.W7x0 module, several cells can be connected in parallel
to each channel, provided that they have the same electrical characteristics.
Principal applications
● The module is suitable for implementing platform, metering or batch scales,
e.g. with pellets, liquids etc., and for measuring forces in technical processes
● In commercial or safety-related applications, the whole system must be certied
by the authorities responsible, e.g. calibratable scales, overload protection etc.
Overview of functions
Taring For taring, the current gross weight is dened as the zero setting.
After this, only additional net weights added to this are displayed.
Scaling After placing a check weight, the equipment is scaled.
Empty warning If the scale remains at zero, an empty warning is displayed
Standstill signal This signal is generated when a stable equilibrium is reached
Zero correction The zero point can be tracked automatically
Di. weighing For continuous increases in weight, the increase per second can
be calculated and output
Error reporting Wire breaks and overloads are displayed; cases where the axi-
mum weight is hugely exceeded are captured and stored
Digital lters Low-pass congurable from 0.01 to 4 seconds
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Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
Hardware
1-3
1
Technical data
1.3 Technical data
General
Resolution: 0.001 % (depending on measuring equipment)
Internal resolution: 218 (~1 to 260,000)
Linearity: 0.005 %
Temperature stability: 0.002 % / °C for cells with 2 mV / V
Digital lter in A/D converter: 7.8 Hz to 822 Hz congurable
Post-lter in controller: 0.24 Hz to 100 Hz congurable
Settling time for 00% load: 50 ms to 3 secs depending on lter
50 and 60 Hz suppression: 100 dB min.
Weighing cell characteristics
Type of weighing cells: DMS weighing cells with 4 or 6 terminals
Sensitivity: 0.5 to 4 mV / V congurable
Cell supply voltage: 10 VDC +/- 0.5 V
Permissible load resistance per channel: > 87 Ω (up to 4 cells connected in parallel)
Terminals:
PCD1|2
PCD3
Plug-in 14-pole spring terminal block for Ø up to
1.5 mm²:
4 405 5002 0
4 405 4998 0 (Type E)
Layout
I/O-connector
Controller
I/O-decoding
Analogue converter
Pre-amplifier
Supply
Terminal
+ U2
+ Sense2
+ Signal2
- Signal2
- Sense2
- U2
GND
+ U1
+ Sense1
+ Signal1
- Signal1
- Sense1
- U1
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
013
0
J
J J J
J: jumpers for 4-wire load cells
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Saia-Burgess Controls AG
Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
Hardware
1-4
1
Functional description
1.3.1 Wiring
The weighing cells are generally provided with a 1.50 to 2.00 m connecting cable.
The wiring to the weighing module is via a 6-core shielded cable and a connection
socket, to which several cells can be connected.
Maximum length of connecting cable: 100 m
X-section for 100 m: 0.75 mm2
for 50 m: 0.50 mm2 (AWG 20)
for 20 m: 0.34 mm2 (AWG 22)
I/O bus interface
The weighing module uses all available addresses on its slot. The input and output
variables at the same address have dierent meanings.
Pin assignment table
Base address Saia PCD®→module Module→Saia PCD
®
+0 Data 0 Data 0
+1 Data 1 Data 1
+2 Data 2 Data 2
+3 Data 3 Data 3
+4 Data 4 Data 4
+5 Data 5 Data 5
+6 Data 6 Data 6
+7 Data 7 Data 7
+8 Command or address bit 0 “1”→Standstill at selected channel
+9 Command or address bit 1 “1”→Near zero at selected channel
+10 Command or address bit 2 “1”→Ready to read at selected channel
+11 Command or address bit 3 “1”→System error at selected channel
+12 Channel: “0”→1, “1”→2 Not connected
+13 “0”→READ, “1”→WRITE Not connected
+14 “0”→DATA, “1”→COMMAND Not connected
+15 “1”→Execute “1” →Busy
1.4 Functional description
The vast majority of force cells work on the same principle and are supplied in
more or less standardised versions. The cells consist of metal bars with sections
that stretch under load and others that are compressed. These sections have
4 strain gauge bridge resistances attached to them, connected electrically to a
jumper.
The jumper carries a stable voltage of 10 VDC. With no load, all resistances
theoretically have the same value, and the signal voltage is 0 V. With a load on
the weighing cell, the resistance value Rd will increase and Rs will decrease;
the resulting signal voltage will change in proportion to the load. At the highest
permissible load, the signal voltage will be 5 mV, 10 mV, 20 mV or 40 mV,
depending on the specication of the weighing cell. The smallest measurable
voltage is about 0.1 µV, giving a resolution of 1 to 200,000 with a cell with a
sensitivity of 2 mV / V.
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Saia-Burgess Controls AG
Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
Hardware
1-5
1
Signal processing
Rd
Rd
Rd Rs
Rs
Supply +
Sense +
Supply -
Sense -
Signal +
Signal -
The feed voltage across the jumper is dependent on the performance of the
voltage regulation, the jumper current, the length of the feed cable and the
temperature. For this reason, it is usual to attach a return wire to the jumper, to
feed the eective jumper voltage back to the analogue converter with zero current
if possible.
1.5 Signal processing
Block diagram
Rd
Rd Rs
Rs
Supply +
Sense +
Supply -
Sense -
Signal +
Signal -
Supply
+ 10 VDC
Preamplifier
+
-
A/D converter
Ref. +
Digital
filter
Ref. -
Postfilter
and
I/O-
interface
PCD I/O-Bus
Gain
● Pre-amplication is by a factor of 16.3
● The reference voltage is reduced to 2.85 V by a voltage divider.
Amplication factor
The analogue converter is equipped with a further amplier; the degree of
amplication is specied by the user. In general, the rule is:
GAIN = the nearest value less than [2.85 / (rating of call * 163)]
Rating GAIN Factor
0.5 mV / V 32 5
1 mV / V 6 4
2 mV / V 8 3
4 mV / V 4 2
Rating means: sensitivity of the cell (mV / V)
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Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
Hardware
1-6
1
Signal processing
Digital lter
The analogue converter is tted with a low-pass lter with a congurable threshold
frequency between 8 Hz and 800 Hz. This frequency is entered in encoded form
from 20 (800 Hz) to 2000 (8 Hz).
Post-lter
A further low-pass lter can be connected downstream of the converter where
required. This derives the average across 2 to 20 measurements. This lter is
automatically activated when it is established that the object to be weighed is
stable, i.e. the dierence between 2 measuring cycles is less than the Gap.
Weighing cycle
Time
Weight
GAP
1 2 3 4 5 6 20
Cycle of the converter
Activation of
Post-filter
Value of weighing
available
Time of weighing (Tw)
Throughout the weighing process, interim results can be read o.
Time required for weighing
Of course, this time is dependent on how quickly the items are placed on the
scale. For this description of the behaviour of the measuring equipment, we will
assume that the weighing unit is loaded in sudden bursts. The digital lter requires
4 acquisition cycles to reach the nal value. From this point, the post-lter takes as
many acquisition cycles as there are values needed to calculate the average (2 to
20, congurable).
Measurement resolution
The measurement resolution (smallest repeatable weight) is dependent on the
time constants of the digital lter and the post-lter. In general, the resolution of a
measurement is greater, the longer the time available for it. The table below gives
an impression of the relationship between settings, time and resolution.
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Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
Hardware
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1
Signal processing
The times listed relate to a step response, i.e. from a sudden full-loading of the
scale until the measurement has stabilised.
Value for the digital lter
Acquisition cycle in ms
Time to nal value in ms
Number of cycles per second
Resolution of analogue values
Post-lter=2 Post-lter=5 Post-lter=10 Post-lter=20
Time for a measurement
in ms
Resolution
Time for a measurement
in ms
Resolution
Time for a measurement
in ms
Resolution
Time for a measurement
in ms
Resolution
20 1.2 4.8 830 2
-10
10 2
-10
12 2
-11
20 2
-12
30 2
-13
50 3 12 333 2
-11
20 2
-11
30 2
-13
40 2
-13
70 2
-14
100 6 24 166 2
-12
40 2
-12
60 2
-13
75 2
-14
130 2
-15
200 12 48 83 2
-13
80 2
-13
120 2
-14
150 2
-15
250 2
-16
500 30 120 33 2
-13
180 2
-13
280 2
-14
380 2
-15
625 2
-16
1000 60 240 16 2
-14
350 2
-14
500 2
-15
750 2
-16
1300 2
-17
2000 120 480 8 2
-15
700 2
-15
1000 2
-16
1500 2
-17
2500 2
-18
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Saia-Burgess Controls AG
Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
2
Programming
2-1
Function boxes
2 Programming
2.1 Function boxes
The deployment of one or more weighing modules is simplest with the FBoxes
WM_Master, WM_Cong, WM_Weigh and WM_Status. The FBoxes WM_Cong,
WM_Weigh and WM_Status are all available with both dynamic and static inputs.
In a FUPLA environment, the FBoxes with dynamic inputs are generally used. With
the FBoxes with static inputs, the user has the choice of setting the input to “1” or
“0”, or of manipulating the input externally. This has the advantage, for example,
that selected functions can be performed in one step within a Graftec program,
and others in a dierent step. If the weight is to be read in each cycle within a
FUPLA program, the Weigh input is set to “1” and the other inputs controlled by
the event are manipulated externally.
If the input „Weigh“ is set constant to „1“, it must be set be during the reset with
„Zero“ to „0“.
Example of the reset with “Zero” to “0”
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Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
2
Programming
2-2
Function boxes
WM_Master
Ths FBox is only programmed once in a weighing application. It controls the
entire data trac from all weighing FBoxes to all weighing modules. In the
Master Box, the data sent to the modules and the data read from the modules is
collated, checked and passed to the application. The other FBoxes are exclusively
concerned with controlling the selected scale as required by the application.
LifeFlag This output reports that a weighing module can no longer be addressed.
Timeout Timeout is set to “1” when the response from a weighing module is
delayed too long.
Address Base address of the defective module
The following FBoxes are programmed once per weighing channel:
Addr Base address of the module slot
Chan Channel number for the module (1 or 2)
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2
Programming
2-3
Data interchange
WM_Cong
The conguration of a weighing module is carried out once when the weighing
application is commissioned, or it can be repeated if necessary, if an operating
parameter changes. All conguration parameters are entered in the Adjust window
for the FBox, where they can be changed online or oine. All inputs react to a
transition from “0” to “1”.
Cong Sends all conguration data to the module addressed, stores the
data permanently in the weighing module and triggers a cold start of
the weighing module. In this process, the zero point of the scale is
determined, so it is important always to run the conguration with an
empty scale. The end of conguration is detected when the “Still” signal is
displayed on reading the status of this channel.
Full This input triggers calibration of the scale with a check weight placed on
it. The scaling of the apparatus is then based on the value entered as a
calibration weight in the Adjust window for the FBox.
Scale The input Scale is not supported by the modules PCD7.W720. It is
reserved for future applications and should be connected to Ground (0 V).
ReadO Reads the extent to which the weighing cell has been overloaded. This
value is stored within the module and is not lost in the event of a supply
failure.
ClearO Resets the overload memory to 0, e.g. after the replacement of a
defective weighing cell.
Error Reports a system error with this scale.
ErrorID Reports the type of error with this scale.
Overload Indicates by what % the nominal value of the weighing cell has been
exceeded.
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Programming
2-4
Overview
WM_Weigh
Weighing and zeroing the scale are controlled by the FBox WM_Weigh. This Box
always returns a result, whether or not the scale has already reached the nal
weight. The Status Box is used to determine the status of the scale. If a “1” appears at the “Still” output, the user can be sure that the scale has reached a stable
nal state. All inputs react to a transition from “0” to “1”.
Weigh Triggers the readout of a weight.
Dweigh Triggers the readout of a dierential weight.
Zero Resets the scale to zero (tare).
Weight Outputs the weight in the scaled unit.
Dweight Outputs the dierential weight in units per second. Please note that the
additional smoothing lter delays the output.
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Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
2
Programming
2-5
Overview
WM_Status
The status of the scale is determined with the FBox WM_Status. The main states
of the scale are:
● The scale is working correctly
● Nothing on the scale (empty)
● The scale is still (with or without anything on it)
A further feature is the stability of the scale. This is dependent on the noise behaviour of the weighing module, the vibration of the base of the scale and the addition
of the item to be weighed.
Status Triggers the readout of the messages: Error, scale empty and scale at a
standstill
Noise Triggers the readout of an indicator value for the stability of the
scale.
Error Reports a system error.
ErrorID Reports the type of system error detected.
Empty If “1”, the scale is empty.
Still If “1”, the scale is at a standstill, and the weight can be read o.
Noise Instability of the scale; range of values 0 to 255. One unit repre-
sents 2
-18
of the nominal loading of the cell.
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Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
2
Programming
2-6
Overview
2.2. Data interchange between Saia PG5® FBoxes and weighing modules
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Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
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Programming
2-7
Overview
2.3 Overview
Inputs Command ags Saia PG5® FBox Resources Outputs
FBox
WM_Master
→LIFE_FLAG LifeFlag
→Timeout Timeout
→Address Address
Cong SET_AMPLIFICATION→
FBox
WM_Cong
Address:
Channel:
←AMPLIFICATION
SET_DFILTER→ ←DFILTER
SET_PFILTER→ ←PFILTER
SET_GAP→ ←GAP
SET_EMPTY→ ←EMPTY
SET_AUTOZERO→ ←AUTOZERO
SET_LOWPASS→ ←LOWPASS
CONFIGURATION→
Full FULL_CALIBRATION→ ←CHECK_WEIGHT
Scale SET_CALIBRATION→
ReadO READ_OVERLOAD→ →OVERLOAD Overload
ClearO CLEAR_OVERLOAD→
→SYSTEM_ERROR Error
→ERROR ErrorID
Weigh READ_WEIGHT→ FBox WM_Weigh
Address:
Channel:
→WEIGHT Weight
Dweigh READ_DWEIGHT→ →DWEIGHT Dweight
Zero ZERO_CALIBRATION→
Status READ_STATUS→ FBox
WM_Status
Address:
Channel:
→EMPTY Empty
→STANDSTILL Still
→SYSTEM_ERROR Error
→ERROR ErrorID
Noise READ_UNSTABILITY→
→NOISE
Noise
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Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
Conguration
3
3-1
3 Conguration
The weighing module will only work correctly if the necessary parameters are
present when the module is started up. These parameters are permanently stored
in the module and are automatically passed to the A/D converter and the computer
at start-up. To guarantee automatic start-up, the parameters must be written to the
weighing module at least once.
All operating parameters are entered in the Adjust window for the FBox WM_Cong.
Sensitivity of connected cell Gain
The target value for amplication is passed to the weighing module in encoded
form.The default setting is 2 mV / V
Table of values:
Gain Weighing cell Coding
1 0
2 1
4 4 mV / V 2
8 2 mV / V 3
16 1 mV / V 4
32 0.5 mV / V 5
64 6
128 7
Set digital lter Dl
The bandwidth of the A/D converter can be preset in a range from 20 to 2,000. This
represents a conversion time of 1.2 to 120 ms.
Filter values selected from the Filter table.
Set post-lter Pl
At the output from the A/D converter, the average of a predened number of
weight measurements is calculated. This number is assigned values from 0.2 to
20. With values 0 and 1, the averaging is deactivated.
Admitted staggering Gap
Gap denes when the post-lter is activated within the weighing cycle. The range
of values is 0 to 255, with 1 representing roughly 1/65,000 of the nominal loading
of the cell. Normal setting: 3 to 20.
In operation, the weighing process is repeated on a cyclical basis. The number of
cycles per second is between 8 and 800, depending on the setting of the digital
lter. If the dierence between 2 weighing cycles is greater than the Gap, the postlter is set to the current actual value. The average of the most recent weighing
cycles is calculated from the point at which the results from successive weighing
cycles vary by less than the Gap.
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Conguration
3
3-2
Weight considered as empty Empty
Empty indicates the maximum weight used to assess whether the weighing vessel
is empty. One unit represents roughly the nominal loading of the cell divided by
30,000, i.e. for a 20 kg weighing cell, one unit will be approx. 0.7 grams.
Enable Autozero Autozero
With A utozero equal to “1”, the scale is automatically reset to zero if it is empty.
The scale is considered to be empty if the residual weight is less than the value
entered for Empty.
Filter for dierential weighing Lowpass
To compensate for short-term uctuations in the ow of material, the dierential
weight is smoothed with a rst-order lter. The value for the time constant for this
low-pass lter can be preset here.
The time constant is passed to the weighing module in encoded form:
Lowpass Time constant for the lter
0 0.25 seconds
1 0.5 seconds
2 1 second
3 2 seconds
4 4 seconds
5 8 seconds
6 16 seconds
7 32 seconds
Check weight
This parameter is set to dierent values for scales calibrated with a check weight
and scales that work with calibrated weighing cells.
Calibration with check weight:
A “1” at the Full input calibrates the scale to the check weight. The check weight
must not exceed the maximum permissible weight for the scale. The actual value
of the check weight is stored as the Check weight parameter, with the format of
the weight display required. If the check weight is not placed on the scale for a
Full calibration, an error message will be generated (bit 6 of the ErrorID).
The check weight should be at least 1/50 of the nominal loading of the weighing
cell.
Example:
Scale: Nominal load for weighing cells: 200kg
Check weight: 50kg
With Check weight = 50,000, the resolution is 1 gram. The display range is then 0
to 200,000 grams.
With Check weight = 500, the resolution is 0.1 kg. The display range is then 0.0 to
200.0 kg.
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Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
Conguration
3
3-3
Functions of the weighing module
Zero_calibration Zero (WM_Weigh)
This command calibrates the scale to its empty state. This takes account of all
errors in the weighing system and the weight of the empty vessels (tare). This
command is normally executed just before the container is lled (this operation
can also be performed automatically).
Weighing Weigh (WM_Weigh)
The readout of the weight is triggered by a positive signal edge at the Weigh input
to the FBox WM_Weigh. The weight can then be taken from the Weight output in
signed integer format.
Dierential weighing Dweigh (WM_Weigh)
The readout of the dierential weight is triggered by a positive signal edge at the
Dweigh input to the FBox WM_Weigh. The dierential weight (change of weight
per second) can then be taken from the Dweight output in signed integer format.
Positive values mean that the weight is increasing, negative values mean it is
decreasing.
Functional ow for calculating the dierential weight
The weighing module calculates the change in weight approx. every 250 ms, and
extrapolates up to 1 second. The same units of weight are used as for recurring
weighing.
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Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
Conguration
3
3-4
Operation:
Acquisition cycles with
a small time constant
Time window
250 ms
T (Time observed)
Change of weight in the time observed
T
Stability of the scale Noise (WM_Status)
The instability of the weighing system can be read with a positive signal edge
at the Noise input to the FBox WM_Status. The instability is dependent on the
noise behaviour of the acquisition system, the vibration of the scale base and
the addition of the item to be weighed. In the next program cycle, a value for this
instability will appear at the Noise output. The range of values is from 0 to 255.
One unit represents 2
-18
of the nominal loading of the cell.
Reading the overload on the weighing cell ReadO (WM_Cong)
This input is used to read o the maximum overload ever reached on the
weighing cells. Most commercially available weighing cells are guaranteed to
withstand overloading up to 150% of their nominal load without damage. But it it
quite common, especially with small weighing cells, for them to be more heavily
overloaded.
The overload read o may range from 110% to 390%. The cell overload is
permanently stored in the weighing module and is overwritten each time a heavier
load is detected.
Clearing the overload memory ClearO (WM_Cong)
This input resets the permanent memory storing the overload value to 0. It is used
when initialising a new module, or in service where e.g. a defective weighing cell is
replaced.
Reading the status of the scale Status (WM_Status)
The readout of the status of the scale is triggered by a positive signal edge at the
Status input to the FBox WM_Status. When this FBox is activated, the data trafc between the weighing module and the Saia PCD® CPU is also checked. If this
data trac is no longer assured, the LifeFlag on the WM_Master Box is set to “1”.
• 1 sec.
Dierential weight =
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Conguration
3
3-5
Status signals:
● Still is an output that indicates when the item is stable on the scale, i.e. the
noise is less than the value dened as the Gap.
Still equal to “1” indicates that a stable value for the weight can be read o.
Of course it is also possible to read o all intermediate values for an increasing
or decreasing weight.
● Empty is an output that indicates that the scale is at 0, i.e. the residual weight
detected is less than the value dened by the Empty parameter. The
permissible range for Empty is from 0 to 255. One unit represents 2
-16
of the
nominal loading of the cell.
● Error This output signals that a system error has been detected in the weighing
module or in the weighing process itself.
As a general rule, all errors in a measuring system are reported with the Error
status signal. At the same time, a description of the type of error is written to the
ErrorID output.
When the Status input is activated, only new errors are captured, while the old errors are cleared.
Error bit in the ErrorID register Description
7 6 5 4 3 2 1 0
1 Cell more than 100% loaded
1 Cell more than 150 % loaded
1 Wire break
1 Malfunction of the module
1 ADC conguration error
1 ADC failure
1 Invalid FULL_CALIBRATION
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Operation of the weighing module
Commissioning | Operation
4
4-1
4 Operation of the weighing module
4.1 Commissioning
The commissioning of a weighing channel involves two steps:
Conguration of the scale
Scaling of the equipment
Conguration
The conguration procedure is described in detail in the section on Conguration
(WM_Cong).
4.1.2. Scaling
Start by running a zero adjustment with Zero on the WM_Weigh Box. Place the
check weight on the scale and activate the Full input on the FBSox WM_Cong.
This scaling must then be checked by removing the weight, running Zero and
weighing the check weight once again with Weigh. If the dierence is too
great, the whole procedure must be repeated. The scaling value is then stored
automatically and reused at each startup.
4.2 Operation
The operation of the scale normally runs as follows:
Run Zero just before weighing, while the scale is still empty. Load the scale. There
are now several possibilities:
● Weigh and analyse continuously with Weigh
● Wait for the status signal Still and read o the nal weight with a one-o Weigh
● During loading of the scale, read o and analyse the dierential weight with
Dweigh on a recurring basis.
Tare calibration can either be performed with Zero before each weighing, or it can
be executed automatically.
Automatic zero adjustment
Zero adjustment (tare) is run automatically where the Autozero parameter is
set to “1”. If the result from the scale over 20 acquisition cycles is less than the
value dened in Empty, the system will treat the scale as empty, and a new zero
adjustment will be carried out.
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Appendix
A
5-1
Icons
A Appendix
A.1 Icons
In manuals, this symbol refers the reader to further information in this manual or other
manuals or technical information documents.
As a rule there is no direct link to such documents.
This symbol warns the reader of the risk to components from electrostatic discharges
caused by touch.
Recommendation: At least touch the Minus of the system (cabinet of PGU connector)
before coming in contact with the electronic parts. It is better to use a grounding wrist
strap with its cable attached to the Minus of the system.
This sign accompanies instructions that must always be followed.
Explanations beside this sign are valid only for the Saia PCD® Classic series.
Explanations beside this sign are valid only for the Saia PCD® xx7 series.
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Manual for PCD2|3.W7x0 │ Document 26-833 ENG07 │ 2018-10-18
Appendix
A
5-2
Address
A.2 Contact
Contact
Saia-Burgess Controls AG
Bahnhofstrasse 18
3280 Murten, Switzerland
Telephone switchboard ........... +41 26 580 30 00
Telephone SBC Support ......... +41 26 580 31 00
Fax .......................................... +41 26 580 34 99
Support
E-mail Support: ...................... [email protected]
Support site: ........................... www.sbc-support.com
SBC site: ................................ www.saia-pcd.com
International representations &
SBC sales companies: ........... www.saia-pcd.com/contact
Repair
Postal address for customers to return products in Switzerland:
Saia-Burgess Controls AG
After sales service
Bahnhofstrasse 18
3280 Murten, Switzerland
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