Flowserve 400MD Logix - Manual (Page 101)

10.19 Logix 3400MD Digital Input (DI) Operation
The DI(LO) is a discrete that is set when the actual position of the actuator is equal or less than the XDTB_MAIN.pos_alert_lo parameter.
To implement, schedule the DI(LO) block to run and set the XDTB_MAIN.pos_alert_lo to the value that you want the trigger point to be.
DI(HI) is a discrete that is set when the actual position of the actuator is equal or greater than the XDTB_MAIN.pos_alert_hi parameter.
To implement, schedule the DI(HI) block and set the XDTB_MAIN.pos_alert_hi to the value that you want the trigger point to be
11 Software Maintenance
Appendix A: Sample Configuration Record
Sample Device Configuration
The following pages provide a printout example of the Function Block Application portion of a Logix 3400MD digital positioner device configuration file. The
printout was generated using the NI-FBUS Configurator application and shows function block parameters and values for a typical control loop. The printout
is shown at the left side of the page. Comments and notes on the configuration are given on the left-hand side.
Glossary
A/D: Also called ADC or analog-to-digital converter. An A/D converts an analog signal into an integer count. This integer count is then used by the micro
controller to process information such as position, pressure and temperature.
D/A: Also called DAC or digital-to-analog converter. A D/A converts an integer count into an analog output signal. The D/A is used to take a number from the
micro controller and command an external device such as a pressure modulator.
EEPROM: Electrically Erasable Programmable Read Only Memory. A device which retains data even when power is lost. Electrically erasable means that data
can be changed. EEPROM have a limited number of times data can be re written.
Micro controller: In addition to an integral CPU (microprocessor), the micro controller has built in memory and I/O functions such as A/D and D/A.
Microprocessor: Semiconductor device capable of performing calculations, data transfer, and logic decisions. Also referred to as CPU (Central
Processing Unit).
Protocol: A set of rules governing how communications messages are sent and received. PV: Primary Variable or Process Variable.
Resolution: Resolution is a number which indicates the smallest measurement which can be made. You will often see Analog-to-Digital (A/D)
converters referred to as a 10-bit A/D or a 12-bit A/D. 10-bit and 12-bit are terms which indicate the total number of integer counts which can
be used to measure a sensor or other input. To determine the total integer count, raise 2 to the power of the number of bits.
Example: 12-bit A/D
Total integer number = 2Number of Bits = 212= 4096
Resolution is the measurement range divided by the maximum integer number.
Logix 3400MD Digital Positioner LGENIM3405-02 11/13
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