CD600 Plus - User's Manual
4.32
In order to make a valve with excursion time = 1 minute open or close 25%, it is required a total time
of 15 seconds (25% of 60 s).
As the minimum width (AWPL) was set to 3sec, the step control will give 5 pulses of 3 seconds
equally distributed in a period of one minute. It will keep this rate while the PID output keeps the
same rate of change. See Figure 4.11.3.
Increasing PID signal acts on output OPEN and decreasing PID signal acts on output CLOSE.
When the control is in Manual mode, the MV increase or decrease keys will change the block output
status as follows:
Key < > Pressed → Output OPEN at high logic level
Key < > Pressed → Output CLOSE at high logic level
In order to have Manual operation, it is necessary to connect the status output of the A/M block to
input B of the Step Control block.
When input C receives a high logic level signal, the block output is switched to the safety condition
defined in parameter CSAF:
CSAF = 0 → Output OPEN and CLOSE at low logic level, the valve remains in the last position.
CSAF = 1 → Output OPEN at high logic level, the valve goes to the fully open position.
CSAF = 2 → Output CLOSE at high logic level, the valve goes to the fully closed position.
TYPE MNEM DESCRIPTION RANGE DEFAULT
I LIA
Incremental input (ΔMV)
0
I LIB MANUAL MODE indicative input 0
I LIC
Addresses 0 to 170 / 225 to
240
0 Input for safety position switching
0 - Last value
1 - Open
2 - Closed
I CSAF Safety Position 0
I CTYP Type of control
0-Open/None/Close 1-On/Off
0
I AWPL Minimum pulse width (in number of cycles) 1 - 1000 2
I AVOT Valve opening time 0 - 3200s 60s
Number of Bytes per Type of Parameter: A = 4 C = 4 L = 6
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