Siemens es7212-1he40-0xb0

By Abdullah Zahid
13 min read
Siemens 6ES7212-1HE40-0XB0 SIMATIC S7-1200 CPU 1212C DC/DC/relay PLC module for motor starter and conveyor control

Siemens 6ES7212-1HE40-0XB0 SIMATIC S7-1200 CPU 1212C DC/DC/relay — Specs, Price, and Alternatives Guide

Controls engineers evaluating the Siemens 6ES7212-1HE40-0XB0 are typically at one specific decision point: relay outputs or solid-state? This is the relay variant of the SIMATIC S7-1200 CPU 1212C, delivering 8 digital inputs, 6 relay digital outputs rated at 2A each, 2 analog inputs, and PROFINET connectivity in a 90mm x 100mm x 75mm package weighing 370 grams. If your load profile includes contactor coils, motor starter solenoids, or general-purpose 24V DC switching where a 10ms relay response time is acceptable, this CPU eliminates the need for external output relay modules and reduces overall panel component count.

If you have already confirmed this is the correct part for your application, check current pricing and availability at LeadTime.ca — ships worldwide.

Who Should Buy the 6ES7212-1HE40-0XB0 — and Who Shouldn't

This CPU is the right choice when all of the following conditions are true for your application:

  • Your outputs drive inductive loads such as contactor coils or relay solenoids where 2A per contact and 30W DC or 200W AC per output is sufficient
  • Your onboard I/O requirement fits within 8 digital inputs (24V DC), 6 digital outputs (relay), and 2 analog inputs (0–10V DC)
  • Your network architecture uses PROFINET Ethernet (ISO/IEC 61784-2:2010) and you have a managed switch available if multi-device connection is needed from a single port
  • Your program logic fits within 100 KB shared program and data memory
  • Your ambient operating environment stays within -20°C to +60°C and relative humidity does not exceed 95% without condensation
  • Your engineering environment runs TIA Portal STEP 7 V20 or higher — this CPU is not compatible with STEP 7 V5.x or older toolchains

If your application requires fast solid-state switching, low electrical noise, or high-cycle-rate outputs, the correct variant is the 6ES7212-1AE40-0XB0 (CPU 1212C DC/DC/DC). If you need more than 100 KB of program memory or more than 8 DI / 6 DO / 2 AI onboard, step up to the CPU 1214C series instead.

On this page:

What the 6ES7212-1HE40-0XB0 Actually Does in a Control System

The Siemens 6ES7212-1HE40-0XB0 is the main processor and control engine within the SIMATIC S7-1200 platform. It executes programmed logic — ladder diagram, structured text, or function block — at each scan cycle, reads the state of its 8 digital inputs and 2 analog inputs, and drives 6 relay output contacts based on that logic. What distinguishes this part from its solid-state sibling is the relay contact architecture: each output is a mechanical relay rated at 2A nominal, 30W DC maximum or 200W AC maximum per contact. That rating is exactly what a standard IEC contactor coil or relay solenoid typically requires, which is why this variant is frequently the first choice for motor starter panels and pump control cabinets.

Beyond basic I/O, the CPU 1212C DC/DC/relay running firmware V4.7 includes 6 high-speed counter channels capable of counting up to 100 kHz, integrated PID controller blocks for closed-loop process control, and a single PROFINET RJ45 port for network communication. The 100 KB shared program and data memory is adequate for small-to-medium control applications, and the CPU supports up to 3 communication modules, 1 signal board, and 2 signal modules to grow I/O capacity as application needs evolve.

Typical System Architecture for the CPU 1212C DC/DC/relay

This CPU sits at the controller layer of the system — between the engineering network above it and the field devices below it. Understanding where it connects in the signal chain helps validate whether a single PROFINET port and 8 DI / 6 DO / 2 AI is sufficient before committing to the design.

  • Engineering PC running TIA Portal STEP 7 V20 or higher connects via Ethernet to a managed industrial switch
  • The 6ES7212-1HE40-0XB0 connects its single RJ45 PROFINET port to that switch — note the CPU has no built-in switch, so multi-device topologies require an external switch
  • An HMI panel (if used) connects to the same managed switch and communicates with the CPU over PROFINET
  • Field sensors and limit switches wire directly to the 8 digital input terminals; analog transducers (0–10V DC) connect to the 2 analog input terminals
  • Relay output terminals connect directly to contactor coils, solenoid valves, or motor starter circuits — each rated up to 2A / 30W DC or 200W AC per contact

Where This CPU Gets Deployed: Industries and Machine Types

In general manufacturing environments, the 6ES7212-1HE40-0XB0 is regularly specified for conveyor and sorting line control where relay outputs energize conveyor motors and diverter solenoids, digital inputs read limit switches and proximity sensors, and PROFINET connects the CPU to an operator HMI. The relay output architecture directly drives contactor coils without intermediate relay modules, reducing panel wiring complexity on machines with 6 or fewer output-switched devices.

Pump and valve sequencing in water treatment and process plants is another consistent application. The 2 analog inputs monitor system pressure or temperature from 0–10V DC transmitters, while relay outputs sequence pump motors and proportional valve pilots. The integrated PID controller block handles the closed-loop pressure or temperature regulation without an additional process controller module.

Building automation and HVAC zone control systems use this CPU to manage damper motors and compressor contactors — loads that relay contacts handle reliably — while Ethernet connectivity links the CPU to a central building management system. Food and beverage batch mixing and filling lines are also common deployments, where relay outputs start mixer motors and heaters, and the high-speed counter channels track ingredient dispensing pulses up to 100 kHz.

Application Typical Deployment
Motor starter and soft-start control Relay outputs drive contactor coils; HSC channels monitor encoder feedback
Pump and valve sequencing Discrete relay outputs control pumps; analog inputs read pressure and temperature
Small conveyor and sorting line Relay outputs energize motors and diverters; PROFINET connects to HMI panel
Building HVAC zone control Outputs control damper motors and compressors; Ethernet links to BMS
Batch mixer with PID temperature control Relay outputs start mixer and heater; PID loop maintains temperature setpoint
Test equipment and assembly lines Digital I/O handles fixture control; analog inputs read sensor feedback

Purchase-Decision Specs at a Glance

Parameter Value
Product Name SIMATIC S7-1200 CPU 1212C DC/DC/relay
Digital Inputs 8 x 24V DC (6 usable for high-speed counting)
Digital Outputs 6 relay contacts — 2A nominal, 30W DC or 200W AC max per contact
Analog Inputs 2 x 0–10V DC, 100k ohm input impedance, 625 µs conversion time
Program/Data Memory 100 KB shared
High-Speed Counters 6 channels up to 100 kHz
Communication 1 x PROFINET RJ45 (ISO/IEC 61784-2:2010), auto-crossover, auto-negotiation
Supply Voltage 24V DC nominal (range: 20.4–28.8V DC)
Operating Temperature -20°C to +60°C
Dimensions / Weight 90mm W x 100mm H x 75mm D / 370 grams

Full technical specifications are available on the product page at LeadTime.ca.

6ES7212-1HE40-0XB0 vs 6ES7212-1AE40-0XB0: Relay or Solid-State?

The two most commonly confused variants are the relay output model (1HE40) and the DC/DC/DC solid-state output model (1AE40). Both share identical CPU core, 100 KB memory, 8 DI / 2 AI, and the same PROFINET communication interface. The difference is entirely in the output section.

Feature 6ES7212-1HE40-0XB0 (Relay) 6ES7212-1AE40-0XB0 (DC/DC/DC)
Output Type Mechanical relay contacts Solid-state transistor outputs
Output Rating 2A nominal, 30W DC or 200W AC max 2A nominal, solid-state 24V DC
Switching Speed ~10ms (mechanical relay) Fast switching, sub-millisecond
Mechanical Wear Yes — finite relay lifetime No mechanical wear
Audible Noise Yes — relay click audible Silent operation
AC Load Support Yes — up to 200W AC per contact No — DC loads only
Best For Contactor coils, motor starters, mixed AC/DC loads High-speed logic, noise-sensitive environments, high-cycle DC loads
Memory / I/O Count Identical to 1AE40 Identical to 1HE40

If your architecture uses relay-switched contactor coils or AC loads and switching frequency is low, the 6ES7212-1HE40-0XB0 is the correct choice — check current availability at LeadTime.ca.

Expert Verdict: When This CPU Earns Its Place and When It Doesn't

The 6ES7212-1HE40-0XB0 is a well-suited choice for any general-purpose machine control application where the output loads are inductive (contactor coils, relay solenoids, motor starters) and switching frequency is modest. The relay output architecture provides inherent galvanic isolation between the CPU logic and the load circuit, eliminates the need for interposing relay modules that would otherwise consume panel space, and handles both AC and DC load circuits — a practical advantage in mixed-voltage panels. The compact 90mm x 100mm x 75mm footprint combined with 6 high-speed counter channels and an integrated PID controller means this CPU can take on process control tasks that would require separate add-on cards on older platforms, all within 100 KB of program and data memory.

The honest limits of this model are worth naming clearly. The 100 KB shared memory ceiling will constrain complex applications with extensive data logging, multi-axis coordination, or dense function block libraries — if your logic is approaching that ceiling, specify the CPU 1214C series instead. The single PROFINET RJ45 port has no integrated switch, meaning you will need an external managed industrial switch for any network topology with more than one downstream device. Relay contacts have a finite mechanical lifetime, making the 1AE40 solid-state variant the correct choice for applications with very high output switching frequencies. And the entire platform requires TIA Portal STEP 7 V20 or higher — if your facility is locked to an older STEP 7 V5.x environment, this CPU is not compatible.

From a procurement standpoint, the 6ES7212-1HE40-0XB0 is an established model in the SIMATIC S7-1200 series with consistent availability through authorized distributors. Typical lead times in standard orders run 2–4 weeks. Volume pricing is available — if you are specifying multiple units across a project or stocking a spare, that conversation is worth having before you place the order. If this matches your system requirements, view current stock and pricing at LeadTime.ca.

For volume pricing or to confirm lead time before committing to a build, contact the LeadTime.ca team directly — we ship worldwide.

Wiring and Installation Overview

The following points cover the key requirements and configurations to verify before installation. For full wiring diagrams and step-by-step procedures, refer to the Siemens SIMATIC S7-1200 system manual.

  • Supply voltage must be 24V DC within the 20.4–28.8V DC range; include an external fuse or circuit breaker rated for the 12A inrush current — the CPU does not include an integrated circuit breaker
  • The 8 digital inputs accept 24V DC signals and support both sourcing and sinking configurations; logic "1" threshold is 15V DC at 2.5 mA — verify sensor output levels before wiring
  • Each of the 6 relay output contacts is rated 2A nominal, 30W DC or 200W AC maximum; never exceed the 2A per contact limit, and install a freewheel diode across any inductive load to protect relay contacts from back-EMF
  • Analog inputs accept 0–10V DC signals only — use shielded twisted pair cable up to 100 meters maximum, with the shield grounded at the sensor end only to prevent ground loops
  • The PROFINET RJ45 port supports auto-crossover, so straight-through or crossover cable is acceptable; use industrial-grade shielded Ethernet cable on the factory floor — not standard office Cat5e

Commissioning the 6ES7212-1HE40-0XB0: What to Verify First

  • Mount the CPU on a 35mm DIN rail, connect 24V DC power, and confirm the RUN LED illuminates green with no ERROR LED active before proceeding to network configuration
  • Install TIA Portal STEP 7 V20 or higher on the engineering PC — this CPU is not compatible with earlier STEP 7 versions — and create a new project selecting CPU 1212C DC/DC/relay
  • Assign a unique IP address and network mask to the CPU within TIA Portal; use the "Search Devices" function to discover and confirm the CPU is online on the same subnet as the engineering PC
  • Map all I/O tags to CPU addresses before writing logic (e.g., digital input 0.0 for emergency stop, digital output 0.0 for conveyor motor relay) and configure high-speed counter or PID blocks as required by the application
  • After downloading the program, verify DI indicator LEDs illuminate when inputs are active and relay outputs energize as programmed — monitor TIA Portal diagnostics for any runtime errors before connecting live loads

Expansion Modules and System Growth Options

The 6ES7212-1HE40-0XB0 supports a defined expansion architecture when onboard I/O is insufficient. The following modules are supported by the CPU 1212C platform:

  • Up to 3 communication modules — for additional PROFINET I/O, serial communication, or gateway functions
  • 1 signal board — a compact plug-in board that adds additional I/O channels directly to the CPU face without consuming a module slot
  • Up to 2 signal modules — digital I/O expansion modules (such as the SM 1222) or analog I/O modules for additional channel count
  • PROFINET I/O devices — distributed I/O can be added across the network, allowing the CPU to control field devices beyond the physical expansion limit of the local rack
  • Maximum current draw with all modules connected is 1200 mA — verify your 24V DC power supply can deliver this load before specifying the fully expanded configuration

What Engineers Get Wrong When Ordering This Part

Before placing your order, work through this checklist. Every item on this list corresponds to a real sourcing error that results in delays, redesign, or field failures.

  1. Confirm output type required: This model has RELAY outputs (not solid-state). If application needs fast switching or low-noise DC output, this is incorrect choice. Specify DC/DC/DC variant instead.
  2. Check power budget: Relay outputs consume significant power (200W AC max). If power distribution is limited, verify relay load does not exceed 30W DC per output group.
  3. Verify I/O count is sufficient: This CPU has exactly 8 DI, 6 DO relay, 2 AI. If more I/O needed, confirm expansion modules are budgeted and available.
  4. Confirm PROFINET connectivity required: This CPU has single RJ45 Ethernet port with no integrated switch. Verify network topology and whether port must be shared or daisy-chained.
  5. Check firmware compatibility: Engineering uses STEP 7 V20 or higher. Do NOT order if environment is locked to STEP 7 V5.x or older versions.
  6. Verify temperature and humidity environment: Operating range -20°C to 60°C with max 95% RH (no condensation). Clarify if application exceeds these limits.
  7. Confirm memory is adequate: 100 KB program/data memory is shared. Complex applications with extensive data logging may require larger CPU model.

If any item on this checklist raises a question, contact the LeadTime.ca team before ordering — we can help confirm the correct variant and check current availability worldwide.

Frequently Asked Questions

Can the 6ES7212-1HE40-0XB0 relay outputs directly drive motor starter contactor coils?

Yes. Each relay contact is rated at 2A nominal and 30W DC or 200W AC maximum, which covers the coil current demand of standard IEC contactors used in motor starter circuits. Always install a freewheel diode across the coil to suppress back-EMF transients that would otherwise degrade relay contact life over time.

What is the difference between the 6ES7212-1HE40-0XB0 and 6ES7212-1AE40-0XB0?

The 1HE40 has mechanical relay digital outputs; the 1AE40 has solid-state transistor outputs. Both share identical CPU core, 100 KB memory, 8 DI, 2 AI, and PROFINET interface. Choose the relay variant (1HE40) for inductive AC or DC loads with low switching frequency; choose the solid-state variant (1AE40) for high-speed logic outputs, noise-sensitive circuits, or high-cycle-rate applications where mechanical wear is a concern.

How many expansion modules can be connected to this CPU?

The CPU 1212C supports up to 3 communication modules, 1 signal board, and 2 signal modules. Total current draw with all expansion modules connected must not exceed 1200 mA at 24V DC. If I/O requirements exceed what this expansion capacity provides, consider stepping up to the CPU 1214C series with additional onboard I/O and memory.

Does this CPU work with TIA Portal on a standard PC Ethernet connection, or is special hardware required?

No special hardware is required. The 6ES7212-1HE40-0XB0 connects directly via its PROFINET RJ45 port to a standard Ethernet network. The engineering PC running TIA Portal STEP 7 V20 or higher must be on the same network subnet as the CPU. The port supports auto-crossover, so a direct PC-to-CPU connection using any Ethernet cable is possible without a managed switch for initial commissioning.

What happens if the analog input receives a signal above 10V DC?

The analog inputs on the 6ES7212-1HE40-0XB0 are rated for a 0–10V DC input range with 100k ohm input impedance. Exceeding this range will produce invalid readings and may cause permanent damage to the analog input circuit. Verify the sensor output signal is within 0–10V DC and does not produce transient overvoltage conditions before wiring to the analog terminal.

What is the typical lead time and is this part available for international shipment?

Standard lead time from authorized distributors is typically 2–4 weeks for the 6ES7212-1HE40-0XB0. LeadTime.ca ships worldwide — current stock levels and exact lead times for your region are visible on the product page or available by contacting the team directly. Always specify the exact part number 6ES7212-1HE40-0XB0 when requesting a quote to avoid substitution with the 1AE40 solid-state variant.

Why Order From LeadTime.ca

  • Ships worldwide — no geographic restriction on orders, including expedited international shipments
  • Stocks and sources hard-to-find SIMATIC S7-1200 variants including the relay output models that are frequently confused or substituted incorrectly by less specialized distributors
  • Volume pricing available — multiple units or full project BOM inquiries handled directly by the team
  • Fast response for lead time confirmation before you commit to a project schedule — avoids the 6–8 week project impact of a wrong part or unexpected delivery delay

At-a-Glance Summary

  • Model: Siemens 6ES7212-1HE40-0XB0 — SIMATIC S7-1200 CPU 1212C DC/DC/relay, firmware V4.7
  • Onboard I/O: 8 digital inputs (24V DC), 6 relay outputs (2A / 30W DC or 200W AC per contact), 2 analog inputs (0–10V DC)
  • Program and data memory: 100 KB shared — adequate for small-to-medium applications; step up to CPU 1214C if more memory is needed
  • High-speed counters: 6 channels up to 100 kHz — supports encoder feedback and ingredient dispensing pulse counting without add-on cards
  • Communication: Single PROFINET RJ45 port, no integrated switch — external managed switch required for multi-device topologies
  • Power supply: 24V DC nominal (20.4–28.8V DC range); 400 mA typical CPU-only draw; 1200 mA maximum with all expansion modules; 12A inrush at 28.8V DC
  • Backup battery runtime: 480 hours typical; real-time clock deviation ±60 seconds per month at 25°C
  • Physical: 90mm x 100mm x 75mm, 370 grams, 35mm DIN rail mount
  • Operating temperature: -20°C to +60°C; storage: -40°C to +70°C; humidity up to 95% RH without condensation
  • Engineering requirement: TIA Portal STEP 7 V20 or higher — not compatible with STEP 7 V5.x or older
  • Expansion: Up to 3 communication modules, 1 signal board, 2 signal modules supported
  • Relay variant alternative: 6ES7212-1AE40-0XB0 for solid-state outputs; CPU 1214C series for more memory and more onboard I/O