General information
Product type designation		SM 1221, DI 16x24 V DC
Supply voltage
Rated value (DC)		24 V
permissible range, lower limit (DC)		20.4 V
permissible range, upper limit (DC)		28.8 V
Input current
from backplane bus 5 V DC, max.		130 mA
Digital inputs
● from load voltage L+ (without load), max.		4 mA; per channel
output voltage / header
supply voltage of the transmitters / header
● present		Yes
Power loss
Power loss, typ.		2.5 W
Digital inputs
Number of digital inputs		16
● in groups of		4
Input characteristic curve in accordance with IEC 61131, type 1		Yes
Number of simultaneously controllable inputs
all mounting positions
— up to 40 °C, max.		16
horizontal installation
— up to 40 °C, max.		16
— up to 50 °C, max.		16
vertical installation
— up to 40 °C, max.		16
Input voltage
● Rated value (DC)		24 V
● for signal "0"		5 V DC at 1 mA
● for signal "1"		15 V DC at 2.5 mA
Input current
● for signal "0", max. (permissible quiescent current)		1 mA
● for signal "1", min.		2.5 mA
● for signal "1", typ.		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
for interrupt inputs
— parameterizable		Yes
Cable length
● shielded, max.		500 m
● unshielded, max.		300 m
Interrupts/diagnostics/status information
Alarms
● Diagnostic alarm		Yes
Diagnostics indication LED
● for status of the inputs		Yes
Potential separation
Potential separation digital inputs
● between the channels, in groups of		4
Degree and class of protection
IP degree of protection		IP20
Standards, approvals, certificates
CE mark		Yes
CSA approval		Yes
UL approval		Yes
cULus		Yes
FM approval		Yes
RCM (formerly C-TICK)		Yes
KC approval		Yes
Marine approval		Yes
Ecological footprint
● environmental product declaration		Yes
Global warming potential
— global warming potential, (total) [CO2 eq]		123 kg
— global warming potential, (during production) [CO2 eq]		12.1 kg
— global warming potential, (during operation) [CO2 eq]		111 kg
— global warming potential, (after end of life cycle) [CO2 eq]		-0.434 kg
Ambient conditions
Free fall
● Fall height, max.		0.3 m; five times, in product package
Ambient temperature during operation
● min.		-20 °C
● max.		60 °C
● permissible temperature change		5°C to 55°C, 3°C / minute
Ambient temperature during storage/transportation
● min.		-40 °C
● max.		70 °C
Air pressure acc. to IEC 60068-2-13
● Storage/transport, min.		660 hPa
● Storage/transport, max.		1 080 hPa
Relative humidity
● Operation at 25 ℃ without condensation, max.		95 %
connection method
required front connector		Yes
Mechanics/material
Enclosure material (front)
● Plastic		Yes
Dimensions
Width		45 mm
Height		100 mm
Depth		75 mm
Weights
Weight, approx.		210 g