Measurement Computing WEB-TEMP - Manual (Page 34)

WEB-TEMP User's Guide Specifications
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Digital input/output
Table 10. Digital input/output specifications
Parameter Specification
Digital type CMOS
Number of I/O 8 (DIO0 through DIO7)
Configuration Independently configured for input or output.
Switch selectable output voltages: +5 V and +3.3 V
Power on conditions
Power on reset is Input mode except when bits are configured to operate as
alarms.
Pull-up/pull-down configuration All pins are connected to 47 kΩ resistors that share a common point accessible
at Pin 22 of the device (PU/D). This pin is floating by default and is user-
configurable via external connection. For pull-up mode, connect this pin to pin
21 (+5V). For pull-down mode, connect this pin to Pin 48 (GND).
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 (+5 V mode) 4 V min, 5.5 V absolute max
Input high voltage (+3.3 V mode) 2.64 V min, 5.5 V absolute max
Input low voltage (+5 V mode) 1 V max, –0.3 V absolute min
Input low voltage (+3.3 V mode) 0.66 V max, –0.3 V absolute min
Output low voltage (IOL = 2.5 mA) 0.6 V max
Output high voltage (IOH = –2.5 mA) 4.3 V min (+5 V mode), 2.7 V (+3.3 V mode)
Note 15: Ground pins on the device labeled GND are isolated from AGND pins and from earth ground.
Temperature alarms
Table 11. 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 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.
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
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. The DIO line goes high when an alarm condition is met.
 Enabled, active low output. The DIO line goes low when an alarm condition is met.
Alarm update rate 1 second
Memory
Table 12. Memory specifications
Parameter Specification
EEPROM 512 bytes for sensor configuration
FLASH 2 MB for device configuration and website storage