| General information |
| Product type designation | SM 1221, DI 8x24 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. | 105 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. | 1.5 W |
| Digital inputs |
| Number of digital inputs | 8 |
| ● in groups of | 2 |
| Input characteristic curve in accordance with IEC 61131, type 1 | Yes |
| Number of simultaneously controllable inputs |
| all mounting positions |
| — up to 40 °C, max. | 8 |
| horizontal installation |
| — up to 40 °C, max. | 8 |
| — up to 50 °C, max. | 8 |
| vertical installation |
| — up to 40 °C, max. | 8 |
| 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 | 2 |
| 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 |
| ● horizontal installation, min. | -20 °C |
| ● horizontal installation, max. | 60 °C |
| ● vertical installation, min. | -20 °C |
| ● vertical installation, max. | 50 °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. | 170 g |
| Approvals / Certificates |