Flowserve 1400 Valtek Logix - Manual (Page 23)

46-23 Flowserve Corporation, Valtek Control Products, Tel. USA 801 489 8611
GLOSSARY
A/D: Also called ADC. Analog-to-digital converter. An
A/D converts an analog signal into an integer count.
This integer count is then used by the microcontroller
to process sensor information such as position,
pressure, and temperature.
D/A: Also called DAC. 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
microcontroller 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 rewritten (typically 100,000 to
1,000,000 writes).
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 Process-
ing Unit).
Protocol: A set of rules governing how communica-
tions messages are sent and received.
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 = 2 Number of Bits = 2 12 = 4096
Resolution is the measurement range divided by the
maximum integer number.
Example: A valve has a 2 inch stroke and a 12-bit A/D
is used to measure position.
Resolution = Stroke/(Maximum Integer for 12-bit) =
2 inch/4096 = 0.000488 inches
Sampling: Taking readings at periodic time intervals.
Serial Channel: Channel which carries serial trans-
mission. Serial transmission is a method of sending
information from one device to another. One bit is
sent after another in a single stream.