数字量输入模块允许将控制器与过程中的数字信号连接。

这为用户提供了下列优势：

• **适应性：
  使用可以根据需要混合的信号模块，用户可以使其控制器准确地满足相关任务的要求。这可以避免产生不必要的投资。可以使用带有 8 个、16 个和 32 个输入/输出通道的模块。
• 灵活性：
  如果任务后续有所扩展，可以升级控制器。更新用户程序非常简单。
•  

• Technical Specifications

  Order number		6ES7221-1BF32-0xB0	6ES7221-1BH32-0xB0
  		DIGITAL INPUT SM 1221, 8DI, 24V DC	DIGITAL INPUT SM 1221, 16DI, 24V DC
  General information
  Product type designation		SM 1221 DI 8x24 VDC	SM 1221 DI 16x24 VDC
  Supply voltage
  Rated value (DC)
  ● 24 V DC		Yes	Yes
  permissible range, lower limit (DC)		20.4 V	20.4 V
  permissible range, upper limit (DC)		28.8 V	28.8 V
  Input current
  from backplane bus 5 V DC, max.		105 mA	130 mA
  Digital inputs
  ● from load voltage L+ (without load), max.		4 mA; per channel	4 mA; per channel
  Output voltage
  Power supply to the transmitters
  ● present		Yes	Yes
  Power loss
  Power loss, typ.		1.5 W	2.5 W
  Digital inputs
  Number of digital inputs		8	16
  ● in groups of		2	4
  Input characteristic curve in accordance with IEC 61131, type 1		Yes	Yes
  Number of simultaneously controllable inputs
  all mounting positions
  — up to 40 °C, max.		8	16
  horizontal installation
  — up to 40 °C, max.		8	16
  — up to 50 °C, max.		8	16
  vertical installation
  — up to 40 °C, max.		8	16
  Input voltage
  ● Type of input voltage		DC	DC
  ● Rated value (DC)		24 V	24 V
  ● for signal "0"		5 V DC at 1 mA	5 V DC at 1 mA
  ● for signal "1"		15 V DC at 2.5 mA	15 V DC at 2.5 mA
  Input current
  ● for signal "0", max. (permissible quiescent current)		1 mA	1 mA
  ● for signal "1", min.		2.5 mA	2.5 mA
  ● for signal "1", typ.		4 mA	4 mA
  Input delay (for rated value of input voltage)
  for standard inputs
  — parameterizable		Yes; 0.2 ms, 0.4 ms, 0.8 ms, 1.6 ms, 3.2 ms, 6.4 ms and 12.8 ms, selectable in groups of four	Yes; 0.2 ms, 0.4 ms, 0.8 ms, 1.6 ms, 3.2 ms, 6.4 ms and 12.8 ms, selectable in groups of four
  for interrupt inputs
  — parameterizable		Yes	Yes
  Cable length
  ● shielded, max.		500 m	500 m
  ● unshielded, max.		300 m	300 m
  Interrupts/diagnostics/status information
  Alarms
  ● Diagnostic alarm		Yes	Yes
  Diagnostics indication LED
  ● for status of the inputs		Yes	Yes
  Potential separation
  Potential separation digital inputs
  ● between the channels, in groups of		2	4
  Degree and class of protection
  Degree of protection acc. to EN 60529
  ● IP20		Yes	Yes
  Standards, approvals, certificates
  CE mark		Yes	Yes
  CSA approval		Yes	Yes
  cULus		Yes	Yes
  FM approval		Yes	Yes
  RCM (formerly C-TICK)		Yes	Yes
  Marine approval
  ● Marine approval			Yes
  Ambient conditions
  Free fall
  ● Fall height, max.		0.3 m; five times, in product package	0.3 m; five times, in product package
  Ambient temperature during operation
  ● permissible temperature range		-20 °C to +60 °C horizontal mounting, -20 °C to 50 °C vertical mounting, 95% humidity, non-condensing
  ● min.		-20 °C	-20 °C
  ● max.		60 °C	60 °C
  ● permissible temperature change		5°C to 55°C, 3°C / minute	5°C to 55°C, 3°C / minute
  Ambient temperature during storage/transportation
  ● min.		-40 °C	-40 °C
  ● max.		70 °C	70 °C
  Air pressure acc. to IEC 60068-2-13
  ● Storage/transport, min.		660 hPa	660 hPa
  ● Storage/transport, max.		1 080 hPa	1 080 hPa
  Relative humidity
  ● permissible range (without condensation) at 25 °C		95 %	95 %
  Connection method
  required front connector		Yes	Yes
  Mechanics/material
  Enclosure material (front)
  ● Plastic		Yes	Yes
  Dimensions
  Width		45 mm	45 mm
  Height		100 mm	100 mm
  Depth		75 mm	75 mm
  Weights
  Weight, approx.		170 g	210 g