6.4.3 GFI - Gravimetric filling instrument
In GFI mode, the electronic weighing system also allows a set point to be set, which the dosing
functionality of the electronic weighing system then automatically doses.
The dosing signals "Coarse flow/Fine flow" can be used to directly control the corresponding
dosing elements (e.g. valves). After the set point is reached, the electronic weighing system
automatically logs the dosed weight in the log memory, performs a tolerance check (only in
checked cycles), corrects the shut-off points of the dosing signals if necessary (only in checked
cycles) and completes the weighing operation autonomously. Optionally, the electronic
weighing system can also empty the scale.
In this weighing operating mode, the dosing is controlled by the electronic weighing system in
a fully-automatic manner. In contrast to a NAWI scale, logging of the individual dosing
operations by an operator command is not required (the electronic weighing system logs every
weighing nevertheless). The scale is therefore tested during verification to see if the set point
setting is always within the legally prescribed limits.
Typically, GFI scales dose continuously in continuous operation, which the electronic weighing
system also supports. In this weighing operating mode, the option also exists to define cycles
that are not zeroed/tared and not checked. This increases the throughput of the scale because
the operations that require stability do not occur in every weighing cycle.
In practice, the dosing process may proceed as follows:
1. PLC sends set point (DR20) and material parameter (DR23) to the electronic weighing
system
2. PLC sends "Start" command (e.g. 1101) to the electronic weighing system
3. The electronic weighing system performs zeroing or tares (based on DR25) (weighing step
1)
4. Coarse/fine dosing phase starts (weighing step 2)
5. If configured and necessary, post-dosing occurs (DR22) (weighing step 3)
6. Dosing result is automatically checked and logged (weighing step 4)
7. Scale is emptied, if necessary (based on setting in DR25) (weighing step 5)
8. The electronic weighing system jumps to weighing step 0 and waits for further commands
or jumps directly back to step 1 (continuous operation).
6.4.4 CWI - Catchweighing instrument / CW - Automatic check weigher
6.4.4.1 CWI - Catchweighing instrument/ CW - Automatic check weigher - Filling
In CWI/CW mode, the electronic weighing system also allows a set point to be set, which the
dosing functionality of the electronic weighing system then automatically doses.
The dosing signals "Coarse flow/Fine flow" can be used to directly control the corresponding
dosing elements (e.g. valves). After the set point is reached, the electronic weighing system
automatically logs the dosed weight in the log memory, performs a tolerance check, corrects
the shut-off points of the dosing signals if necessary and completes the weighing operation
autonomously. Optionally, the electronic weighing system can also empty the scale.
Parameter assignment/addressing
6.4 Operating modes
Technology module TM SIWAREX WP351 HF
Operating Instructions, 01/2020, A5E47521010-AA 55