Meriam M2110P SMART PRESSURE GAUGE - Manual (Page 19)

19
User’s Manual Dwg No 9R141-IR
13. P6 & P7 – SETPOINT (Set1 & Set2)
SetPoint Model
These registers define the pressure points at which the SPDT relays will energize. The relay will
energize when the pressure exceeds its corresponding value, and de-energize when the pressure drops
below the value (minus deadband; Register P8). P6 defines the SET1 relay, and P7 defines the SET2
relay. P6 and P7 settings are completely independent of each other; either may be greater, less than, or
equal to the other.
Current Loop Model
These registers define the 4 to 20 mA output value. P6 (SET1) sets the 4.00 mA output and P7 (SET2)
sets the 20.00 mA output. (Thus, the output “zero” is defined by SET1, and the “span” is defined by
SET2 – SET1.) When the pressure is at the P6 value, the output will be 4.00 mA; when the pressure is
at the P7 value, the output will be 20.00 mA. Other pressures provide an output that is linearly scaled
between the two values. For values beyond the defined range, however, the output is limited from
4.00 to 20.38 mA. The P6 (4 mA) register can be set greater than the P7 (20 mA) register, to create a
reverse acting output. The limits are –20% to +120% full scale, but P6 and P7 cannot be set equal.
Data Entry
Refer to the Step by Step table below for detailed instructions.
These registers are entered in the current Engineering Unit used by the gauge. (The current
Engineering Unit is illuminated during edit of these registers.) For example, if the gauge is set to read
in InH
2
O (at 20°C), and a value of 110 is put into the P6 register, the SET1 relay will energize at 110
InH
2
O (at 20°C).
In
Program Mode, the indicators “SET1”, “SET2”, and “4-20mA” will illuminate as appropriate to
assist in identifying the register. For example, when scrolling to and/or editing P6, “SET1” will be
illuminated, indicating that SET1 is being edited. Likewise for P7 and “SET2”. Also, “4-20mA” will
be illuminated if the gauge is a Current Loop model, to indicate that the 4-20mA range is being edited.
Automatic Update
If the Engineering Unit is changed, the value in the P6 and P7 registers will automatically change to
reflect the new Engineering Unit. This allows changing the Engineering Unit in Measure Mode
without affecting the outputs. For the above example, changing the Engineering Unit to inches of
mercury will automatically update the P6 register to energize at 8.077 inches of mercury, which is
equivalent to 110 InH
2
O (at 20°C).
Also, if the water density reference temperature (P3) is changed, and the current Engineering Unit is
water column based, these registers will update as appropriate. For the above example, changing the
reference temperature to 4°C will automatically update the P6 register to energize at 109.81 InH
2
O (at
4°C), which is equivalent to 110 InH
2
O (at 20°C).