Description
The 6ES7321-1BH10-0AA0 is a Siemens SIMATIC S7-300 SM321 Digital Input Module — the workhorse 24V DC input module for the S7-300 PLC system. “6ES7” = SIMATIC S7 legacy (S7-300/400), “321” = Digital Input (DI) module family, “1BH10” = 16× DI 24V DC, channel-to-channel and channel-to-backplane isolation (galvanically isolated), “0AA0” = standard version without specific options.
- 6ES7321-1BH10-0AA0 → 16 digital inputs, 24V DC (sink/source compatible — 20.4–28.8V DC range), galvanically isolated (input circuit isolated from backplane bus and from groups — actually BH10: 16 inputs in 1 group with 1 common M terminal? Wait — 321-1BH10 datasheet: 16 DI, 24V DC, isolated — the isolation is between input channels and backplane (bus), and the 16 inputs share 2 common terminals (M0.0 / M0.1 — 8 pts per M). So it’s “group-isolated” per spec: 1 group of 16, but internal sub-grouping 8+8 with 2 M terminals). Input delay programmable 0.1 ms / 0.5 ms / 3 ms / 12.8 ms (4 selectable via STEP 7 — for debounce / noise rejection). Each input has hardware interrupt capability (rising/falling edge — configurable in STEP 7 HW config) and diagnostic interrupt (wire break can be detected if sensor supply monitored externally).
- S7-300 context: Module occupies 1 slot in a S7-300 rack (6ES7390-1…) — e.g., 6ES7315-2EH14-0AB0 (CPU 315-2 PN/DP) + rack + PS307 (power supply 6ES7307-1…) + SM321 (DI) + SM322 (DO) + SM331/332 (AI/AO). The SM321-1BH10 sits right of the CPU in slot 4+ (slots 1=PS, 2=CPU, 3=optional IM, 4–11=I/O).
- BH10 vs other 321 variants:
- 6ES7321-1BH00-0AA0 = 16× DI 24V DC, non-isolated (cheaper, shares reference with backplane — NOT recommended for noisy environments)
- 6ES7321-1BH10-0AA0 (your item) = 16× DI 24V DC, isolated (recommended — most common 24V DC DI for S7-300)
- 6ES7321-1BH50-0AA0 = 16× DI 24V DC, high-density, non-isolated, high-speed (for fast counting/app)
- 6ES7321-1BL00-0AA0 = 32× DI 24V DC, isolated (bigger)
- 6ES7321-1BP00-0AA0 = 64× DI (rare)
⚠️ Important for Buyers: S7-300 is legacy but still widely supported — newer S7-1500 has replaced S7-300 for new designs, but S7-300 remains dominant in installed base (2000s–2020s plants). If you need exact spare / repair, 6ES7321-1BH10-0AA0 is the correct p/n. If new design, consider S7-1500 + DI modules (6ES7521-…) — but wiring & rack form factor differ (S7-1500 uses slimmer 25mm/35mm modules vs S7-300 40mm “ET 200M style” — actually S7-300 modules are 40mm wide, S7-1500 25/35mm — not intercompatible). Firmware/config via STEP 7 (Classic, v5.x) or TIA Portal (v11+) — both support S7-300 + SM321.
Key Features
- Inputs: 16× Digital Input, 24V DC (sink/source — 20.4–28.8V DC)
- Isolation: Galvanic isolation between input channels and backplane bus (1 group of 16, 2× M terminals — 8 pts per M)
- Input Delay: Programmable 0.1 / 0.5 / 3 / 12.8 ms (debounce / noise rejection)
- Interrupt Capability: Hardware interrupt on rising/falling edge (configurable in STEP 7 HW Config), Diagnostic interrupt (wire break — if external sensor supply monitored)
- Compatible Sensors: 3-wire DC sensors (PNP wiring preferred: sensor +24V → PNP sensor → input Y□ → 0V; NPN also works with wiring reversal — S7-300 DI 24V is sink/source compatible per common M polarity)
- Backplane Current: 5V backplane ≈ 10 mA (drawn from rack PS); 24V backplane negligible (sensor supply is external — module does NOT supply 24V to sensors! Must provide external 24V DC PSU for sensors, e.g., PS307 24V or SITOP)
- Country of Origin: Germany / EU (Siemens AG)
Technical Specifications (6ES7321-1BH10-0AA0 — 16× DI 24V DC, Isolated)
Parameter | Specification |
|---|---|
Model / Order Code | 6ES7321-1BH10-0AA0 (Siemens SIMATIC S7-300 SM321 Digital Input Module) |
Series | SIMATIC S7-300 (legacy — succeeded by S7-1500 for new designs) |
Inputs | 16× Digital Input, 24V DC (sink/source compatible) |
Input Voltage Range | 20.4 – 28.8 V DC (typical 24V DC nominal) |
Input Current (typ) | ≈ 7 mA @ 24V DC (per input — determines sensor sinking/sourcing load) |
Isolation | Galvanic isolation: Input ↔ Backplane bus; Internal: 16 inputs in 1 group with 2× M terminals (8 pts per M common) |
Input Delay (prog.) | 0.1 ms / 0.5 ms / 3 ms / 12.8 ms (selectable in STEP 7 HW Config — for debounce) |
Input Type | Type 1/2/3 sensor compatible (IEC 61131-2) — 3-wire DC sensors typical |
Cable Length (max) | Shielded: 1000 m (static); Unshielded: 600 m (static) — typical for 24V DC DI |
Interrupts | Hardware interrupt (rising/falling edge) — per-input configurable; Diagnostic interrupt (wire break — if external supply monitored) |
Backplane Bus Current | 5V: ≈ 10 mA (from rack PS307); 24V: negligible (sensor 24V is external PSU, NOT from backplane) |
Power Dissipation | ≈ 3.5 W (typical — from backplane + input current dissipation) |
Indicators (LED) | 16× green I/O LEDs (input active = ON), SF (group fault), 24V LED (if ext 24V present at term?) — actually SM321 has per-point LED + green “24V” LED on front showing external sensor supply presence at terminal M/L+? Wait SM321 itself doesn’t have 24V — front has “24V” LED that lights when external 24V sensor supply is wired to terminal L+ / M correctly — yes, there’s a front LED bar “24V” that monitors the external sensor supply fed to the terminal block (L+ in, M out to sensors) |
Programming SW | STEP 7 Classic (v5.5+ SPx) / TIA Portal (v11+ — S7-300 support in TIA up to v18/19 depending) |
Operating Temp. | 0 … +60 °C (horizontal); 0 … +40 °C (vertical with adjacent modules — S7-300 rack derating rule) |
Dimensions (W×H×D) | 40 mm(W) × 125 mm(H) × 120 mm(D) — standard S7-300 single-slot width |
Weight | ≈ 0.2 kg |
Mounting | S7-300 rack (6ES7390-1AE80-0AA0 etc.) — slots 4–11 for I/O |
Standards | CE, UL, cUL, FM, RCM, KC, RoHS |
Country of Origin | Germany / EU (Siemens AG) |
Warranty & After-Sales
- Factory new units: 12 months warranty
- Refurbished units: 3-6 months warranty (bench: insert into test S7-300 rack + PS307 + CPU → HW Config detect → force ON each DI via 24V source → verify LED + input tag in STEP 7 monitor)
- Technical support for:
- S7-300 rack composition (PS307 → CPU → IM360/361 if ET200M remote → SM321 in slots 4+)
- Wiring (external 24V DC PSU → L+ / M terminals on SM321 front → sensor +24V leg → sensor → input Y□ → M; M terminals: 2× M for 16 inputs — 8 pts each common)
- Sink vs Source wiring (PNP sensor preferred: +24V→sensor brown, blue→0V, black→input Y□, M→0V; module accepts both — just ensure M polarity matches sensor type)
- STEP 7 / TIA HW Config (insert SM321-1BH10 → address default I0.0–I1.7 (16 bits = 2 bytes) → download → monitor table)
- Interrupt configuration (HW Config → SM321 properties → Interrupt → enable rising/falling per input → OB40 called on event)
- Migration note (S7-300 → S7-1500: SM321 not compatible with S7-1500 rack — if new design, use 6ES7521-1BL00-0AB0 etc.; wiring different form factor)
- Optional: S7-300 rack (6ES7390-1AE80-0AA0 / 6ES7390-1AF30-0AA0), PS307 (6ES7307-1BA00-0AA0 2A / 6ES7307-1EA00-0AA0 5A / 6ES7307-1KA02-0AA0 10A), CPU (6ES7312-1AE13-0AB0 etc.), SM322 DO modules, SM331 AI, STEP 7 / TIA license
Delivery Time
- Standard delivery: 3-5 working days (stock NOS)
- Express shipping available upon request
Why Choose Our Store
- Genuine Siemens SIMATIC S7-300 modules — not gray-market (backplane PHY & isolation critical for plant uptime)
- Global supply network with competitive pricing on S7-300 legacy spares
- Expertise in S7-300 system composition (rack + PS + CPU + SM321 wiring, STEP 7 HW Config, interrupt OB40 setup)
- Comprehensive technical documentation (SM321 terminal layout, sink/source wiring diagram, TIA slot map, OB40 interrupt example)
- Responsive customer service and support
Applications
- S7-300 PLC Digital Input Acquisition: Plant-wide S7-300 racks (CPU 315/317) — SM321-1BH10 collects 16× 24V DC sensor signals (prox switches, photo eyes, limit switches, pushbuttons, float switches) — isolated version protects backplane from field noise.
- Retrofit / Spare for Existing S7-300 Lines: Exact p/n 6ES7321-1BH10-0AA0 — drop-in for failed DI module in existing S7-300 rack (mining, water treatment, automotive, food & beverage — S7-300 everywhere).
- High-Noise Environments: Isolated BH10 (vs non-isolated BH00) — galvanic isolation input↔backplane — essential in VFD-heavy plants, weld shops, power substations where ground loops/common-mode noise could corrupt backplane.
- Interrupt-Driven Fast Detection: Hardware interrupt capability — e.g., high-speed prox on conveyor → rising edge triggers OB40 → fast response (sub-ms depending on OB priority) — better than cyclic scan for critical events.
- Migration Holdover: While S7-1500 is current, many plants standardize on S7-300 spares for 10–20 year lifecycle — stock NOS SM321 as cold spare strategy.
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