USB-5201 User's Guide
Specifications
24
Note 6:
The analog inputs are configured to run continuously. Each channel is sampled twice per second.
The maximum latency between when a sample is acquired and the temperature data is provided
by the USB unit is approximately 0.5 seconds. Throughput to CompactFlash memory card is
limited to 1 S/s per channel.
Digital input/output
Table 5. Digital input/output specifications
Digital type
CMOS
Number of I/O
8 (DIO0 through DIO7)
Configuration
Independently configured for input or output.
Power on reset is input mode unless bit is configured for alarm.
Pull up/pull-down configuration
All pins pulled up to +5 V via 47 K resistors (default). Pull down to ground
(GND) also available.
Digital I/O transfer rate (software
paced)
Digital input – 50 port reads or single bit reads per second typ.
Digital output – 100 port writes or single bit writes per second typ.
Input high voltage
2.0 V min., 5.5 V absolute max.
Input low voltage
0.8 V max., -0.5 V absolute min.
Output low voltage (IOL = 2.5 mA)
0.7 V max
Output high voltage (IOH = -2.5 mA)
3.8 V min.
Note 7:
All ground pins on the device (pins 9, 19, 28, 38) are isolated from earth ground. If a connection
is made to earth ground when using digital I/O 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.
Temperature alarms
Table 6. Temperature alarm specifications
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
Memory
Table 7. Memory specifications
EEPROM
1,024 bytes isolated micro reserved for sensor configuration
256 bytes USB micro for external application use
256 bytes USB micro reserved for data logging configuration
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