Measurement-computing USB-TC-AI Instrukcja Użytkownika Pobierz pdf (Strona 20)

USB-TC-AI User's Guide Specifications

Temperature alarms

Table 12. Temperature alarm specifications

Parameter

Specification

Number of alarms

8 (one per digital I/O line)

Alarm functionality

Each alarm controls its associated digital I/O line as an alarm output. The input to each

alarm may be any of the analog temperature input channels. When an alarm is enabled, its

associated I/O line is set to output (after the device is reset) and driven to the appropriate

state determined by the alarm options and input temperature. The alarm configurations are

stored in non-volatile memory and are loaded at power on. Alarms will function both in

data logging mode and while attached to USB.

Alarm input modes

 Alarm when input temperature > T1

 Alarm when input temperature > T1, reset alarm when input temperature goes below T2

 Alarm when input temperature < T1

 Alarm when input temperature < T1, reset alarm when input temperature goes above T2

 Alarm when input temperature is < T1 or > T2

Note: T1 and T2 may be independently set for each alarm.

Alarm output modes

 Disabled, digital I/O line may be used for normal operation

 Enabled, active high output (digital I/O line goes high when alarm conditions met)

 Enabled, active low output (digital I/O line goes low when alarm conditions met)

Alarm update rate

1 second

Counter

Table 13. CTR I/O specifications

Parameter

Specification

Pin name

CTR

Number of channels

Resolution

32-bits

Counter type

Event counter

Input type

TTL, rising edge triggered

Input source

CTR screw terminal

Counter read/writes rates

(software paced)

Counter read: system dependent, 33 to 1000 reads per second.

Counter write: system dependent, 33 to 1000 reads per second.

Schmidt trigger hysteresis

20 mV to 100 mV

Input leakage current

±1.0 µA typ

Input frequency

1 MHz max

High pulse width

500 nS min

Low pulse width

500 ns min

Input high voltage

4.0 V min, 5.5 V absolute max

Input low voltage

1.0 V max, –0.5 V absolute min

Note 13: All ground pins are common and are isolated from earth ground. If a connection is made to earth

ground with both the counter (CTR) and conductive thermocouples, the thermocouples are no longer

isolated. In this case, thermocouples must not be connected to any conductive surfaces that may be

referenced to earth ground.

Memory

Table 14. Memory specifications

Parameter

Specification

EEPROM

1,024 bytes isolated micro reserved for sensor configuration

256 bytes USB micro for external application use

1 2 ... 15 16 17 18 19 20 21 22 23 24

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