How to Select an Interface Relay for PLC Outputs
A step-by-step guide to matching PLC output type, coil voltage and current, contact rating, and socket style when selecting an interface relay.
The Siemens SIMATIC S7-1200 CPU 1212C AC/DC/RLY 6ES7212-1BG50-0XB0 is a compact PLC with an 85-264 V AC power supply, 8 integrated 24 V DC digital inputs, and 6 relay outputs rated 2 A resistive. It holds 150 KB of program memory and 500 KB of data memory, offers 20 KB of retentive storage, and connects over an integrated 2-port PROFINET interface.
The AC/DC/RLY power stage means this CPU runs directly from 120/230 V AC and switches its 6 outputs through relays rated 2 A resistive or 200 W on an AC lamp load, which suits mixed AC/DC field wiring without an external interposing relay bank. Pick this 8 DI / 6 DO 1212C over the 1211C when the application needs the extra 2 relay outputs and the 6-HSC-at-100 kHz counting capability for local encoder or flow-meter inputs; move up to the 1214C if the I/O count or 4 MB work memory of this CPU becomes the constraint. A SIMATIC Memory Card is required for firmware updates and recommended for retentive-data backup.
Fits standalone machine control and small process skids that mix AC-driven field devices with 24 V DC sensors: packaging cells, material-handling stations, and utility skids where relay outputs directly switch contactors or solenoid valves.
| Product type designation | CPU 1212C AC/DC/relay |
|---|---|
| Firmware version | V4.1 |
| FW update possible | Yes |
| Product function: I&M data | Yes; I&M0 to I&M3 |
| Product function: Isochronous mode | Yes; For PROFINET only |
| Product function: SysLog | Yes |
| Engineering with: Programming package | STEP 7 V21 or higher |
| Rated value (AC): 120 V AC | Yes |
|---|---|
| Rated value (AC): 230 V AC | Yes |
| permissible range, lower limit (AC) | 85 V |
| permissible range, upper limit (AC) | 264 V |
| Line frequency: permissible range, lower limit | 47 Hz |
| Line frequency: permissible range, upper limit | 63 Hz |
| Current consumption (rated value) | 70 mA at 120 V AC; 38 mA at 240 V AC |
|---|---|
| Current consumption, max. | 330 mA at 120 V AC; 200 mA at 240 V AC |
| Inrush current, max. | 20 A; at 264 V |
| I2t | 0.8 A2·s |
| Part number | 6ES7212-1BG50-0XB0 |
|---|---|
| Type designation | CPU 1212C AC/DC/relay |
| Brand | Siemens |
| Condition | New, factory sealed |
| Source | Siemens and its authorised distributors |
| Warranty | Manufacturer warranty |
| Lifecycle status | Active, in production |
| EAN | 4047623412830 |
| ETIM class | EC000236 |
| eCl@ss | 27242207 |
| for backplane bus (5 V DC), max. | 1 000 mA; Max. 5 V DC for SM and CM |
|---|
| 24 V encoder supply: 24 V | Yes; 20.4 to 28.8V |
|---|---|
| 24 V encoder supply: Short-circuit protection | Yes |
| 24 V encoder supply: Output current, max. | 300 mA |
| Power loss, typ. | 4 W |
|---|
| Work memory: integrated | 650 kbyte |
|---|---|
| Work memory: integrated (for program) | 150 kbyte |
| Work memory: integrated (for data) | 500 kbyte |
| Load memory: integrated | 8 Mbyte |
| Load memory: Plug-in (SIMATIC Memory Card), max. | 32 Gbyte; with SIMATIC memory card |
| Backup: present | Yes |
| Backup: maintenance-free | Yes |
| Backup: without battery | Yes |
| for bit operations, typ. | 37 ns; / instruction |
|---|---|
| for word operations, typ. | 30 ns; / instruction |
| for floating point arithmetic, typ. | 74 ns; / instruction |
| Number of elements (total) | 4 000; Blocks (OB, FB, FC, DB) and UDTs |
|---|---|
| OB: Number of free cycle OBs | 100 |
| OB: Number of time alarm OBs | 20 |
| OB: Number of delay alarm OBs | 20 |
| OB: Number of cyclic interrupt OBs | 20; with minimum OB 3x cycle of 1 ms |
| OB: Number of process alarm OBs | 50 |
| OB: Number of DPV1 alarm OBs | 3 |
| OB: Number of isochronous mode OBs | 1 |
| OB: Number of startup OBs | 100 |
| OB: Number of asynchronous error OBs | 4 |
| OB: Number of synchronous error OBs | 2 |
| OB: Number of diagnostic alarm OBs | 1 |
| Retentive data area (incl. timers, counters, flags), max. | 20 kbyte |
|---|---|
| Flag: Size, max. | 8 kbyte; Size of bit memory address area |
| Local data: per priority class, max. | 64 kbyte; max. 16 KB per block |
| I/O address area: Inputs | 1 kbyte; All inputs are in the process image |
|---|---|
| I/O address area: Outputs | 1 kbyte; All outputs are in the process image |
| Process image: Inputs, adjustable | 1 kbyte |
| Process image: Outputs, adjustable | 1 kbyte |
| Number of modules per system, max. | 6 |
|---|---|
| number of expansion boards (SB, CB, BB) | 1 |
| number of signal modules (SM) | 6; depends on the number of CMs |
| number of communications modules (CM) | 3 |
| Clock: Hardware clock (real-time) | Yes |
|---|---|
| Clock: Backup time | 480 h; Typical |
| Clock: Deviation per day, max. | 2 s; at 25 °C |
| Clock synchronization: on Ethernet via NTP | Yes |
| Number of digital inputs | 8; Integrated |
|---|---|
| of which inputs usable for technological functions | 8; HSC (High Speed Counting) |
| Sourcing/sinking input | Yes |
| Number of simultaneously controllable inputs all mounting positions: up to 40 °C, max. | 8 |
| Input voltage: Rated value (DC) | 24 V |
| Input voltage: for signal "0" | 5 V DC or 0.5 mA |
| Input voltage: for signal "1" | 15 V DC at 2.5 mA |
| Input delay (for rated value of input voltage) for standard inputs: parameterizable | 0.1 / 0.2 / 0.4 / 0.8 / 1.6 / 3.2 / 6.4 / 10.0 / 12.8 / 20.0 μs; 0.05 / 0.1 / 0.2 / 0.4 / 0.8 / 1.6 / 3.2 / 6.4 / 10.0 / 12.8 / 20.0 ms |
| Cable length: shielded, max. | 500 m; 50 m for technological functions |
| Cable length: unshielded, max. | 300 m; for technological functions: No |
| Number of digital outputs | 6; Relays |
|---|---|
| Switching capacity of the outputs: with resistive load, max. | 2 A |
| Switching capacity of the outputs: on lamp load, max. | 30 W with DC, 200 W with AC |
| Output delay with resistive load: "0" to "1", max. | 10 ms; max. |
| Output delay with resistive load: "1" to "0", max. | 10 ms; max. |
| Switching frequency: of the pulse outputs, with resistive load, max. | Not recommended |
| Relay outputs: Number of relay outputs | 6 |
| Relay outputs: Number of operating cycles, max. | mechanically 10 million, at rated load voltage 100 000 |
| Cable length: shielded, max. | 500 m |
| Cable length: unshielded, max. | 150 m |
| Number of analog inputs | 0 |
|---|
| Number of analog outputs | 0 |
|---|
| Connectable encoders: 2-wire sensor | Yes |
|---|
| Number of PROFINET interfaces | 1 |
|---|
| Interface type | PROFINET |
|---|---|
| Isolated | Yes |
| automatic detection of transmission rate | Yes |
| Autonegotiation | Yes |
| Autocrossing | Yes |
| Interface types: RJ 45 (Ethernet) | Yes; X1 |
| Interface types: Transmission rate, max. | 100 Mbit/s |
| Interface types: Number of ports | 2 |
| Interface types: integrated switch | Yes |
| Protocols: IP protocol | Yes; IPv4 |
| Protocols: PROFINET IO Controller | Yes |
| Protocols: PROFINET IO Device | Yes |
| Protocols: SIMATIC communication | Yes |
| Protocols: Open IE communication | Yes; Optionally also encrypted |
| Protocols: Web server | Yes |
| Protocols: Media redundancy | Yes |
| PROFINET IO Controller: Transmission rate, max. Services | 100 Mbit/s |
| PROFINET IO Controller: PG/OP communication | Yes; encryption with TLS V1.3 pre-selected |
| PROFINET IO Controller: Isochronous mode | Yes |
| PROFINET IO Controller: IRT | Yes |
| PROFINET IO Controller: Dynamic Frame Packing (DFP) | Yes |
| PROFINET IO Controller: PROFIenergy | Yes; per user program |
| PROFINET IO Controller: Prioritized startup | Yes |
| PROFINET IO Controller: Number of IO devices with prioritized startup, max. | 16 |
| PROFINET IO Controller: Number of connectable IO Devices, max. | 31 |
| PROFINET IO Controller: Of which IO devices with IRT, max. | 31 |
| PROFINET IO Controller: Number of connectable IO Devices for RT, max. | 31 |
| PROFINET IO Controller: of which in line, max. | 31 |
| PROFINET IO Controller: Number of IO Devices that can be simultaneously activated/deactivated, max. | 8 |
| PROFINET IO Controller: Updating time Update time for IRT | The minimum value of the update time also depends on the communication component set for PROFINET IO, on the number of IO devices and the quantity of configured user data. |
| PROFINET IO Controller: for send cycle of 1 ms | 1 ms to 16 ms |
| PROFINET IO Controller: for send cycle of 2 ms | 2 ms to 32 ms |
| PROFINET IO Controller: for send cycle of 4 ms Update time for RT | 4 ms to 64 ms |
| PROFINET IO Controller: for send cycle of 4 ms | 4 ms to 512 ms |
| PROFINET IO Device Services: PG/OP communication | Yes; encryption with TLS V1.3 pre-selected |
| PROFINET IO Device Services: Isochronous mode | No |
| PROFINET IO Device Services: IRT | Yes |
| PROFINET IO Device Services: Dynamic Frame Packing (DFP) | No |
| PROFINET IO Device Services: PROFIenergy | Yes; per user program |
| PROFINET IO Device Services: Prioritized startup | Yes |
| PROFINET IO Device Services: Shared device | Yes |
| PROFINET IO Device Services: Number of IO Controllers with shared device, max. | 2 |
| PROFINET IO Device Services: Asset management record | Yes |
| Supports protocol for PROFINET IO | Yes |
|---|---|
| PROFIsafe | No |
| PROFIBUS | No |
| OPC UA | Yes; OPC UA Server |
| AS-Interface | No |
| Protocols (Ethernet): TCP/IP | Yes |
| Protocols (Ethernet): DHCP | Yes |
| Protocols (Ethernet): SNMP | Yes |
| Protocols (Ethernet): DCP | Yes |
| Protocols (Ethernet): LLDP | Yes |
| Number of connections: Number of connections, max. | 128; via integrated interfaces of the CPU and connected CPs / CMs |
| Number of connections: Number of connections reserved for ES/HMI/web | 10 |
| Number of connections: Number of connections via integrated interfaces | 88 |
| Number of connections: Number of S7 routing paths | 16 |
| Redundancy mode: PROFINET system redundancy (S2) | No |
| Redundancy mode: PROFINET system redundancy (R1) Media redundancy | No |
| Redundancy mode: MRP | Yes; as MRP redundancy manager and/or MRP client |
| Redundancy mode: MRP interconnection, supported | Yes |
| Redundancy mode: MRPD | Yes; Requirement: IRT |
| Redundancy mode: Number of stations in the ring, max. | 50 |
| SIMATIC communication: PG/OP communication | Yes; encryption with TLS V1.3 pre-selected |
| SIMATIC communication: S7 routing | Yes |
| SIMATIC communication: S7 communication, as server | Yes |
| SIMATIC communication: S7 communication, as client | Yes; only PUT/GET |
| SIMATIC communication: User data per job, max. | See online help (S7 communication, user data size) |
| Open IE communication: TCP/IP | Yes |
| Open IE communication: Data length, max. | 64 kbyte |
| Open IE communication: several passive connections per port, supported | Yes |
| Open IE communication: ISO-on-TCP (RFC1006) | Yes |
| Open IE communication: UDP | Yes |
| Open IE communication: DHCP | Yes |
| Open IE communication: DNS | Yes |
| Open IE communication: SNMP | Yes |
| Open IE communication: DCP | Yes |
| Open IE communication: LLDP | Yes |
| Open IE communication: Encryption | Yes; Optional |
| Web server: supported | Yes |
| Web server: HTTPS | Yes |
| Web server: web API | Yes |
| Web server: Number of sessions, max. | 30 |
| Web server: HTTP request body, max. | 131 072 byte |
| Web server: User-defined websites | Yes |
| OPC UA: Runtime license required | Yes; "Basic" license required |
| OPC UA: OPC UA Server | Yes; data access (read, write, subscribe), method call, runtime license required |
| OPC UA: Application authentication | Yes |
| OPC UA: Security policies | available security policies: None, Basic128Rsa15, Basic256Rsa15, Basic256Sha256, Aes128Sha256RsaOaep, Aes256Sha256RsaPss |
| OPC UA: User authentication | "anonymous" or by user name & password |
| OPC UA: Number of sessions, max. | 10 |
| OPC UA: Number of subscriptions per session, max. | 5 |
| OPC UA: Sampling interval, min. | 100 ms |
| OPC UA: Publishing interval, min. | 200 ms |
| OPC UA: Number of server methods, max. | 20 |
| OPC UA: Number of monitored items, recommended max. | 1 000 |
| OPC UA: Number of server interfaces, max. | 2 |
| OPC UA: Number of nodes for user-defined server interfaces, max. | 2 000 |
| Further protocols: MODBUS | Yes; MODBUS RTU/TCP |
| S7 communication: supported | Yes |
|---|---|
| S7 communication: as server | Yes |
| S7 communication: as client | Yes |
| S7 communication: User data per job, max. | See online help (S7 communication, user data size) |
| Number of connections: overall | PG Connections: 4 reserved; HMI Connections: 4 reserved / 82 max; S7 Connections: 78 max; Open User Connections: 78 max; Web Connections: 2 reserved / 80 max; Total Connections: 10 reserved / 88 max |
| Number of login stations for message functions, max. | 32 |
|---|---|
| number of subscriptions, max. | 250 |
| number of tags/attributes for subscriptions, max. | 2 000 |
| Program alarms | Yes |
| Number of configurable program messages, max. | 5 000 |
| Number of loadable program messages in RUN, max. | 2 500 |
| Number of simultaneously active program alarms: Number of program alarms | 600 |
| Number of simultaneously active program alarms: Number of alarms for system diagnostics | 100 |
| Status block | Yes; Up to 8 simultaneously (in total across all ES clients) |
|---|---|
| Single step | No |
| Profiling | Yes |
| Status/control: Status/control variable | Yes |
| Status/control: Variables | Inputs/outputs, memory bits, DBs, distributed I/Os, timers, counters |
| Number of variables, max.: of which status variables, max. | 200; per job |
| Number of variables, max.: of which control variables, max. | 200; per job |
| Forcing: Forcing | Yes |
| Forcing: Forcing, variables | Peripheral inputs/outputs |
| Forcing: Number of variables, max. | 200 |
| Diagnostic buffer: present | Yes |
| Diagnostic buffer: Number of entries, max. | 500 |
| Diagnostic buffer: of which powerfail-proof | 100 |
| Traces: Number of configurable Traces | 4 |
| Traces: Memory size per trace, max. | 512 kbyte |
| Diagnostics indication LED: RUN/STOP LED | Yes |
|---|---|
| Diagnostics indication LED: ERROR LED | Yes |
| Diagnostics indication LED: MAINT LED | Yes |
| Motion Control | Yes |
|---|---|
| Number of available Motion Control resources for technology objects | 800 |
| Required Motion Control resources: per speed-controlled axis | 40 |
| Required Motion Control resources: per positioning axis | 80 |
| Required Motion Control resources: per synchronous axis | 160 |
| Required Motion Control resources: per external encoder | 80 |
| Required Motion Control resources: per output cam | 20 |
| Required Motion Control resources: per cam track | 160 |
| Required Motion Control resources: per probe | 40 |
| Required Motion Control resources: Number of available Extended Motion Control resources for technology objects | 40 |
| Required Extended Motion Control resources: per cam (1 000 points and 50 segments) | 2 |
| Required Extended Motion Control resources: for each set of kinematics | 30 |
| kinematics functions: kinematics with up to 4 interpolating axes | Yes |
| kinematics functions: kinematics with 5 or more interpolating axes | No |
| kinematics functions: user-defined kinematics | No |
| kinematics functions: SIMATIC Safe Kinematics | No |
| Positioning axis: Number of positioning axes at motion control cycle of 4 ms (typical value) | 10 |
| Counter | Yes |
|---|---|
| Number of counters | 8 |
| Counting frequency, max. | 100 kHz; Ia.0 to Ia.5: 100 kHz (80 kHz in quadrature mode), Ia.6 to Ia.7: 30 kHz (20 kHz in quadrature mode) |
| Frequency measurement | Yes |
| controlled positioning | Yes |
| Number of position-controlled positioning axes, max. | 8 |
| Number of positioning axes via pulse-direction interface | Up to 4 with SB 1222 |
| PID controller | Yes |
| Number of pulse outputs | 8; individually assigned to CPU and Signal Board |
| Limit frequency (pulse) | 100 kHz |
| Potential separation digital inputs: Potential separation digital inputs | Yes; field side to logic: 707 V DC (type test) |
|---|---|
| Potential separation digital inputs: between the channels | No |
| Potential separation digital inputs: Number of potential groups | 1 |
| Potential separation digital outputs: Potential separation digital outputs | Relays |
| Potential separation digital outputs: between the channels | No |
| Potential separation digital outputs: Number of potential groups | 1 |
| Interference immunity against discharge of static electricity: Interference immunity against discharge of static electricity acc. to IEC 61000-4-2 | Yes |
|---|---|
| Interference immunity to cable-borne interference: Interference immunity on supply lines acc. to IEC 61000-4-4 | Yes |
| Interference immunity against voltage surge: Interference immunity on supply lines acc. to IEC 61000-4-5 | Yes |
| Interference immunity against conducted variable disturbance induced by high-frequency fields: Interference immunity against high-frequency radiation acc. to IEC 61000-4-6 | Yes |
| Emission of radio interference acc. to EN 55 011: Limit class A, for use in industrial areas | Yes; Group 1 |
| IP degree of protection | IP20 |
|---|
| Siemens Eco Profile (SEP) | Siemens EcoTech |
|---|---|
| CE mark | Yes |
| UL approval | Yes |
| cULus | Yes |
| FM approval | No |
| RCM (formerly C-TICK) | Yes |
| KC approval | Yes |
| Marine approval | Yes |
| Ecological footprint: environmental product declaration Global warming potential | Yes; type 2 acc. to ISO 14021 |
| Ecological footprint: global warming potential, (total) [CO2 eq] | 61.1 kg |
| Ecological footprint: global warming potential, (during production) [CO2 eq] | 12.4 kg |
| Ecological footprint: global warming potential, (during operation) [CO2 eq] | 49.2 kg |
| Ecological footprint: global warming potential, (after end of life cycle) [CO2 eq] | -0.63 kg |
| PROFINET Security Class | 1 |
|---|---|
| signed firmware update | Yes |
| Secure Boot | Yes |
| Free fall: Fall height, max. | 0.3 m; five times, in product package |
|---|---|
| Ambient temperature during operation: min. | -20 °C; No condensation |
| Ambient temperature during operation: max. | 40 °C; 40 °C horizontal or 30 °C vertical at max. voltages and max. specifications |
| Ambient temperature during operation: horizontal installation, min. | -20 °C; No condensation |
| Ambient temperature during operation: vertical installation, min. | -20 °C; No condensation |
| Ambient temperature during storage/transportation: min. | -40 °C |
| Ambient temperature during storage/transportation: max. | 70 °C |
| Air pressure acc. to IEC 60068-2-13: Operation, min. | 540 hPa |
| Air pressure acc. to IEC 60068-2-13: Operation, max. | 1 140 hPa |
| Air pressure acc. to IEC 60068-2-13: Storage/transport, min. | 540 hPa |
| Air pressure acc. to IEC 60068-2-13: Storage/transport, max. | 1 140 hPa |
| Altitude during operation relating to sea level: Installation altitude, min. | -1 000 m |
| Relative humidity: Operation, max. | 95 %; no condensation |
| Vibrations: Vibration resistance during operation acc. to IEC 60068-2-6 | 3.5 mm from 5 - 8.4 Hz, 1g from 8.4 - 150 Hz |
| Vibrations: Operation, tested according to IEC 60068-2-6 | Yes |
| Shock testing: tested according to IEC 60068-2-27 | Yes; IEC 68, Part 2-27 half-sine: strength of the shock 15 g (peak value), duration 11 ms |
| Pollutant concentrations: SO2 at RH < 60% without condensation | S02: < 0.5 ppm; H2S: < 0.1 ppm; RH < 60 % condensation-free |
| Programming Programming language: LAD | Yes |
|---|---|
| Programming Programming language: FBD | Yes |
| Programming Programming language: SCL | Yes |
| Know-how protection: User program protection/password protection | Yes |
| Know-how protection: Copy protection | No |
| Know-how protection: Block protection | Yes |
| Access protection: protection of confidential configuration data | Yes |
| Access protection: Protection level: Write protection | Yes |
| Access protection: Protection level: Read/write protection | Yes |
| Access protection: Protection level: Complete protection | Yes |
| Access protection: User administration | Yes; device-wide and centralized |
| Access protection: Number of users | 100 |
| Access protection: Number of groups | 100 |
| Access protection: Number of roles | 50 |
| Cycle time monitoring: adjustable | Yes |
| Width | 70 mm |
|---|---|
| Height | 125 mm |
| Depth | 100 mm |
| Weight, approx. | 373 g |
|---|
| Miscellaneous Manufacturer Declara- | tion |
|---|
| Net weight | 0.373 kg |
|---|---|
| Package dimensions | 136 × 80 × 110 mm |
| Country of origin | CN |
| Shipping weight | 0.873 kg |
| Ships from | Türkiye |
| Dispatch | 13 Nov |
| Stock | In stock |
Source: manufacturer data · Last verified: 01 Nov 2026
No documents are on file for this part yet.
Ask us for the datasheetThe rated current of CPU 1212C AC/DC/relay is 2 A.
The rated operational voltage of CPU 1212C AC/DC/relay is 85–264 V AC.
The tariff (HS) code on file for CPU 1212C AC/DC/relay is 85371091.
The EAN (GTIN) of CPU 1212C AC/DC/relay is 4047623412830.
CPU 1212C AC/DC/relay ships from Türkiye. Shipping calculated at checkout · import duties and taxes paid on arrival. Stock items are dispatched within 1–2 business days.
A step-by-step guide to matching PLC output type, coil voltage and current, contact rating, and socket style when selecting an interface relay.
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