Advantech PCI-1710UL Instrukcja Użytkownika Pobierz pdf (Strona 7)

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16-7

IPC Chassis

Video Surveillance

Serial Comm. Cards

Device Servers

Display Solutions

Panel Computers

Fanless Panel PCs

Operator Panels

Industrial Motherboards

Embedded IPCs

Mobile Computers

IPC Peripherals

DAQ

Ethernet Switches

Signal Conditioning

USB DAQ

SBCs and Backplanes

Pre-Conﬁgured Systems

Isolation Protection

Isolation circuits are used to protect sensitive measurement circuitry from interference

currents or voltages. These circuits are useful when the external voltage (from a transducer)

is separeted from the measurement hardware.

Keeping The Output Values After System Reset

When the system is hot reset (power is not shut off), the Advantech’s DAQ cards with this

function can either retain the last digital (or analog) output values, or return to its default

conﬁguration, depending on jumper setting. This practical function eliminates danger

caused by misoperation during unexpected system reset.

LSB - Least Signiﬁcant Bit

Onboard FIFO Memory

FIFO is the abbreviation of “First-In, First-Out”. It functions as a “buffer” memory, which

plays an important role in the data acquisition device. You can either enable or disable

the interrupt request of the FIFO buffer. While the interrupt request for FIFO is enabled,

you can further specify whether the interrupt request will be sent whenever one sampling

takes place or when the FIFO buffer is half saturated. Advantech’s data acquisition cards

with onboard FIFO memory enables a continuous high-speed data transfer with more

predictable performance on Windows systems.

Onboard Programmable Counter

Advantech’s multifunction cards provide a programmable counter to generate a pacer

trigger for the A/D conversion. The counter chip is an 82C54 or equivalent, which includes

three 16-bit counters on a 10 MHz clock. One counter is used as an event counter for

counting events coming from the input channels. The other two are cascaded together to

make a 32-bit timer for a pacer trigger.

Optical Isolators

Optical isolators are used with digital circuitry to shield high voltage signals from affecting

digital circuitry.

PCI Mastering Data Transfer

Advantech’s high-speed DA & C cards support PCI-Bus mastering DMA for high-speed

data transfer and gap-free analog input and analog output. By setting aside a block of

memory in the PC, the DA&C cards performs bus-mastering data transfers without CPU

intervention, setting the CPU free to perform other more urgent tasks such as data analysis

and graphic manipulation. The function allows users to run all I/O functions simultaneously

at full speed without losing data.

Plug & Play Function

Advantech DAQ cards fully comply with the PCI spectication Rev 2.2 and thus are Plug

& Play devices. During card installation, it is virtually unnecessary to set any jumpers

or DIP switches. Instead, all bus-related conﬁgurations such as base I/O address and

interrupts are conveniently taken care of by the Plug & Play function.

Polling

Polling is the simplest method for detecting a unique condition and then taking action. This

involves a software loop that contains all the required measurement, analysis, decision-

making algorithms and planned actions. The data acquisition program periodically tests the

system’s clock or external trigger input to sense a transition. Whenever a transition occurs,

the program then samples each of the inputs and stores their values in a “frame”. A frame

is simply a list that contains the values representing the speciﬁed inputs at a given time.

The frames can be stored in RAM, disk or other types of memory. Each time the program

senses a clock “tick”, the inputs are scanned and converted, and a new frame is added to

memory. In this mode, generic computers can support an acquisition rate of about 10 kHz.

In addition, the PC is continuously busy when the polling loop is under operation,

and hence no other tasks can be serviced. When an application cannot tolerate these

characteristics, interrupt techniques may be needed.

Programmable Power-Up States

With this function, all output lines are user-conﬁgurable for logic high or logic low when

the system is powering up. User-conﬁgurable power-up states are useful for ensuring that

the data acquisition card powers up in a known state. Power-up states are programmed

in the EEPROM through the driver. The default settings are all set to 0.

PWM - Pulse Width Modulation

Pulse width modulation (PWM) technology is widely used for industrial applications such

as measurement, motor control, power control and so on. It offers a simple way for digital

control logic to create an analog equivalence. By using Advantech’s high-resolution counter

cards, the duty cycle of a square wave could be modulated to encode some speciﬁc analog

signal levels so they can be used to control many electronic devices.

Resolution

Resolution is the smallest change that a measurement instrument can sense. Resolution

is normally speciﬁed in bits.

S.E. Input - Single Ended Input

A single-ended conﬁguration is the best when you need analog measurements against

respect to a common external ground. This conﬁguration is also appropriate when there

is no practical way to bring both a signal ground and an analog ground (AGND) back to

the system‘s input terminals.

Shielding

An extra layer of conductive material surrounding a wire to prevent external electrical

signals from interfering with the signal on the wire.

SPDT Relay - Single-Pole Dual-Throw Relay

SPST Relay - Single-Pole Single-Throw Relay

TTL - Transistor Transistor Logic

Watchdog Timer

The watchdog timer is a software-conﬁgurable feature used to set critical outputs to safe

states in the event of a software failure. It will activate if there is a loss of communication

between the application and the data acquisition card. If the card does not receive a

watchdog clear software command within the interval time speciﬁed for the watchdog

timer, the outputs go to a user-deﬁned safe state and remain in that state until the watchdog

timer is disabled and new values are written by the software.

After the watchdog timer expires, the card ignores any writes until the watchdog timer

is disabled. Users can set the watchdog timer timeout period through WDT register to

specify the amount of time that must elapse before the watchdog timer expires. The

counter on the watchdog timer is conﬁgurable up to (232-1) x 100 ns (approximately

seven minutes) before it expires.

Glossary

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