Page 48 MSI-3750CS RF Weighmeter • User Guide
3750CS
C
ELL
S
CALE RF DIGITAL WEIGHT INDICATOR
®
9) Delay – Any Set Point can be delayed by up to 10 seconds (10000 ms). Often used to prevent
spurious Set Point outputs.
10) On/Off – Any Set Point can be turned on or off independently from the rest without losing any
programmed parameters.
11) All Set Points On/Off – Used to disable the operation of all 32 Set Points.
Operator Relationship, 2 Threshold Set Points
The CellScale can perform In-bounds and Out-of-bounds checking or grading by using the dual threshold feature
of the Set Points. By specifying both a “Value 1” and a “Value 2” and establishing whether the values are to be
“ANDed” or “ORed” the user can have complete control over the action of the Set Points.
For example, a Set Point can trip when the weight is >100kg AND <200kg which provides an in-bounds
comparison. A Set Point can trip when the weight is <100kg OR >200kg which provides an out-of-bounds
comparison.
The CellScale does not prevent you from entering >100kg AND >200kg which would trip when the weight was
over 200kg. Just make sure your formula makes sense.
The Trigger Type parameter allows advanced capabilities such as Set Points that are conditional on weight and
totals. For example set Value 1 to >1000kg with a trigger type of Gross, and set Value 2 to
≥
100000kg with a
trigger type of Total. Set the Operator Relationship to “OR”. This will yield a Set Point that trips on each load
over 1000kg, and stays tripped when the total load is
≥
100000kg.
Preact, Postact, and Deadzone
To illustrate the effect of these three parameters, let’s assume a set point is set for >1000kg. The value placed
in Preact, Postact, or Deadzone is 20kg:
Preact – Set Point trips on >980kg (1000-20) and off at <980kg.
Postact – Set Point trips on >1020kg (1000+20) and off at <1020kg.
Deadzone – Set Point trips on at 1000kg. Turns off at 980kg.
Although the CellScale allows it, it never makes sense to program a Preact and a Postact for the same Set Point,
since they would cancel each other out. However, it is sometimes desirable to combine Preact or Postact with
Deadzone. This would provide hysteresis to the relay or hopper valve and prevent “chatter”. To illustrate this,
building on our previous example: Set point value is >1000kg, preact is 20kg, deadzone is 4kg:
Set Point trips on at 980kg, trips off at 976kg
When a Set Point is set for “less than”, then Preact, Postact, and Deadzone work in the opposite direction.
Let’s again assume a set point is set for 1000kg, but now <1000kg. The value placed in Preact, Postact,
or Deadzone is 20kg:
Preact – Set Point trips on <1020kg (1000+20) and off at >1020kg.
Postact – Set Point trips on <980kg (1000-20) and off at >980kg.
Deadzone – Set Point trips on at <1000kg. Turns off at 1020kg.
For dual value Set Points, Preact, Postact, and Deadzone apply equally to both values with the same rules
illustrated above.
SET POINT SETUP MENU
To program multiple Set Points, is recommended that you use the CellScale Terminal Interface program. The
terminal interface is somewhat faster than scrolling through buried menus in the 3750CS. However, there are
times when a computer to plug into the CellScale is not available, or the CellScale is located inconveniently,
that the 3750CS menus are useful. Also two Set Point features exist solely on the 3750CS and are independent
of CellScale programming. These are local Set Point message outputs and display modes. These must be
programmed locally at the 3750CS.
The Set Point Setup Menu has 22 choices. Not all menu items are needed for simple set points. The following is
a brief description of the function of each Set Point menu.
ALL SET POINTS (ALL SP)
Used to disable and enable all 32 Set Points at once. This parameter is stored in the CellScale, and therefore any
3750CS can disable the Set Points for the entire Cell.
