Preferred Instruments PCC-IV, Instruction Manual

Page: 130 / 135

PCC-IV Instruction Manual (Rev. 0.1) Page 6-45 Section 6
– Blockware Functions
Technical Reference
F116 [TOT] Totalizer (Integrator with Pulse Output)
Function TOT is a signal integrator with a scaled pulse Output. The primary application of the TOT Block is to drive
a counter for flow totalization. TOT can connect to a DOUT , TOUT , or ROUT Block to drive an external physical
counter. TOT can also be connected to a COUNT Block, and the COUNT Block Output can be displayed via a
Panel Data Screen Tag.
100% Input Counts/Hr (Parameter 2) determines the
TOT Output pulse scaling as follows: If the Input is a constant
100%, Then TOT produces (Parameter 2) Pulses (or Counts) per hour. The TOT Block Output is normally "0", each
Block Output pulse is a "1" for exactly one scan. Example: If the TOT Input is a 0-100% signal from a steam flow
meter that is calibrated for 0-75,000 lb/hr steam flow, set Parameter 2 to "7500" to make every pulse equivalent to
10 lbs of steam.
Input Cutoff % (Parameter 1): The calibration of some flowmeters tends to drift near 4 mA (0%). This can cause
false flow totalization when there is no flow. Inputs less than (Parameter 1) are ignored, and no pulse Outputs are
generated. Negative Inputs do not generate a pulse Output.
Disable Input (Parameter 3, and Input 2): By default,
TOT is Enabled and totalizes because the defaults are: Input
2 is Block 2 ( D0 or Low), and Alarm Disable is ACTIVE HI (Parameter 3 = 1). However, Blockware can use the
Disable Input (Input 2) to selectively Disable totalization, that is force the TOT Block Output to be a "0". Parameter
3 determines if the Disable signal is "Active HI", or "Active LO" as follows:
Parameter 3 Disable Input Mode
1 (Active HI) 0 Enabled
1 (Active HI) 1 Disabled
0 (Active LO) 0 Disabled
0 (Active LO) 1 Enabled
---------------------------------------------------------------------------------------------
NAME: TOT SINGLE USE FUNCTION: N OUTPUT TYPE: D
---------------------------------------------------------------------------------------------
Input Type Description Notes
_____________________________________________________________________________________________
1 A INPUT BLOCK
2 D DISABLE BLOCK
Parameter Description Default Max Min Code Notes
_____________________________________________________________________________________________
1 INPUT CUTOFF % 0.00 100.00 0.00 2
2 100% INPUT COUNTS/HOUR 1000 18000 60 2
3 DISABLE INPUT ACTIVE LO/HI:
0=LO, 1=HI 1 1 0 2
F117 [DSW] Discrete Switch
Function DSW is used to switch the Block Output between one of
two discrete Input signals under control of a discrete Select signal.
The concept is like an SPDT relay or 3 port solenoid valve. When
the Select signal is "0" the A Input is selected and passed to the
DSW
Block Output. When Select = "1", the “B” signal is passed to
the Output. The Block Output changes instantaneously when the
Select Input changes.
---------------------------------------------------------------------------------------------
NAME: DSW SINGLE USE FUNCTION: N OUTPUT TYPE: D
---------------------------------------------------------------------------------------------
Input Type Description Notes
_____________________________________________________________________________________________
1 D A INPUT
2 D B INPUT
3 D SELECT INPUT (0 = A, 1 = B)
No Parameters
A
B
Select
Output
0=A, 1=B