SIMATIC S7-300 SM321 Digital Input, 16 DI, 24 V DC

Product Description

The SIMATIC S7-300 SM 321 digital input module provides 16 sourcing inputs for 24 V DC applications and integrates seamlessly into S7-300 backplanes via a 20‑pin front connector. Inputs are electrically isolated in a group of 16 with a 500 V DC isolation test voltage, ensuring robust separation from the backplane bus. The module supports proximity sensors (BEROs) including 2-, 3-, and 4-wire types, with permissible quiescent current up to 1.5 mA for 2-wire devices. Input characteristics conform to IEC 61131 type 1, with typical input current of 7 mA and input delays from 1.2 to 4.8 ms for both transitions. Status is indicated by a green LED per channel; no interrupts or diagnostics are provided. Designed for reliable operation, it supports up to 16 simultaneously controlled inputs in both horizontal (to 60 °C) and vertical (to 40 °C) mounting positions. With compact dimensions of 40 x 125 x 117 mm and approximate weight of 200 g, the module delivers a typical power loss of 3.5 W and minimal backplane current draw of 10 mA.

Key Features

• •16 sourcing digital inputs at 24 V DC
• •Electrical isolation in group of 16
• •IEC 61131 type 1 input characteristics
• •Green LED status per channel
• •Typical input delay 1.2 to 4.8 ms
• •20‑pin front connector wiring
• •Supports 2‑wire BEROs up to 1.5 mA

Buy Options

Condition, indicative price, stock, and lead time. Confirm current availability via RFQ.

Specifications

Module type

SM 321 Digital Input

Inputs

16 sourcing (24 V DC)

Input characteristics

IEC 61131 type 1

Input current (signal "1")

typ. 7 mA

Input delay

1.2 to 4.8 ms (0→1 and 1→0)

Rated input voltage

24 V DC

Signal levels

"1": -13 to -30 V, "0": +30 to -5 V (ref L+)

Electrical isolation

Between channels and backplane bus; in groups of 16

Isolation test voltage

500 V DC

Simultaneously controlled inputs

16 (horizontal to 60 °C, vertical to 40 °C)

Backplane current consumption

max. 10 mA

Power loss

typ. 3.5 W

Status display

Green LED per channel

Diagnostics / interrupts

None

Sensor support

2-/3-/4-wire proximity switches (BEROs)

2-wire BERO quiescent current

max. 1.5 mA

Wiring

20-pin front connector

Cable length

Unshielded max. 600 m; shielded max. 1000 m

Dimensions (W x H x D)

40 x 125 x 117 mm

Weight

approx. 200 g

Model number

6ES7321-1BH50-0AA0

Part #

6ES7321-1BH50-0AA0

Category

PLCs/Machine Control

Category

VDC Logic I/O Module

Weight

0.48 lbs

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