Siemens SIMATIC ET 200M Selection

Siemens ET 200M Distributed I/O System Selection and Engineering Maintenance Guide

System Overview: Distributed Extension of S7-300 I/O

SIMATIC ET 200M is a classic modular distributed I/O system from Siemens, with a protection level of IP20, designed specifically for control cabinet installation. Its biggest advantage lies in the ability to directly use the signal, communication, and functional modules of the S7-300 automation system, extending the I/O capabilities of the central controller to the field while retaining the rich module ecosystem of the S7-300. Whether it is discrete control in manufacturing or continuous measurement in process industry, ET 200M can efficiently communicate with the upper master station (such as S7-300, S7-400, S7-1500 or third-party controllers) through PROFIBUS DP or PROFINET.

This series supports up to 12 I/O modules (depending on the interface module), with a maximum transmission rate of 12 Mbps (PROFIBUS DP) or 100 Mbps (PROFINET), and has hot swapping capability - provided an active bus module is used. In addition, ET 200M can also be used for redundant systems (S7-400H, S7-400F/FH) to meet high availability requirements. According to Siemens' product lifecycle information, the ET 200M family is scheduled to be discontinued in 2023, and spare parts will continue to be supplied for at least ten years thereafter. Therefore, maintaining and upgrading existing systems will be an important issue for future engineers.

Interface module selection: from standard to high feature, from DP to PN

The core of ET 200M is the interface module (IM), which determines the communication protocol, I/O capacity, and advanced functions of the site. The current mainstream models include:

2.1 IM153-1 Standard Type (6ES7153-1AA03-0XB0)

Positioning: Economical, suitable for most manufacturing environments.

Parameters: Up to 8 S7-300 modules; Backplane bus power supply 5 V/1 A; PROFIBUS DP slave, automatic baud rate detection up to 12 Mbps; Supports SYNC/FREEZE and direct data exchange (inter station communication).

Limitations: Advanced features such as clock synchronization, timestamps, and redundant HART operations are not supported.

Application: Production lines with ordinary switch quantities, simple analog quantities, and non real time requirements.

2.2 IM153-2 High Characteristic Type (6ES7153-2BA10-0XB0)

Positioning: Process industry, redundant systems, applications that require timestamps.

Parameters: Up to 12 modules; Backboard 5 V/1.5 A; Also supports 12 Mbps DP. Compared to IM153-1, there is an increase in:

Timestamp: Accuracy of 1 ms (up to 8 modules) or 10 ms (12 modules), capable of recording the rising/falling edges of digital signals, caching up to 15 messages, with a maximum of 20 signals per message.

Redundancy capability: It can be paired with another IM153-2 (requiring redundant bus module 6ES7195-7HD10-0XA0) to form a redundant I/O slave station for S7-400H.

Support redundant switching and firmware updates for HART modules.

Clock synchronization: Synchronized with PROFIBUS DP clock, with an accuracy of 1 ms.

Application: Chemical, power, water treatment with quality requirements, and occasions requiring fault safety (F-I/O).

2.3 IM153-4 PN (PROFINET interface)

Provide two versions:

Standard version (6ES7153-4AA01-0XB0): PROFINET IO device, integrated dual port switch, supports 100 Mbps full duplex, up to 12 modules, I/O capacity of 192 bytes input/output. Please note: If there are devices in the network that do not support LLDP (Neighbor Discovery Protocol), a Micro Memory Card of at least 64 KB must be inserted.

High performance version (6ES7153-4BA00-0XB0): Added support for PROFIsafe fail safe module and HART module on the basis of the standard version, and supports PROFINET system redundancy (S2 mode, compatible with S7-400H) and MRP media redundancy.

Key selection points:

If PROFIBUS DP is still dominant on site and redundancy or timestamps are required, choose IM153-2; Choose IM153-1 for regular applications.

It is recommended to use PROFINET for the new project, with priority given to IM153-4 PN HF, in order to expand the F module and HART in the future.

Pay attention to the total current limit of the backplane: IM153-1 has a maximum of 1 A, and IM153-2/4 PN has a maximum of 1.5 A. Before installation, calculate the 5V consumption of all I/O modules to avoid exceeding the limit.

Hot swappable and active bus module

Hot swapping allows for the replacement of I/O modules during system operation without the need for power outage. To achieve hot plugging, an Active Bus Module and corresponding DP rail must be used. Siemens provides the following components:

Active bus module usage order number

Used for placing power modules and IM, with cover 6ES7195-7HA00-0XA0

Used for accommodating two standard width modules (such as 2AI) with two 40mm wide I/O modules 6ES7195-7HB00-0XA0

Used to accommodate one wide module (such as FM) with one 80mm wide I/O module 6ES7195-7HC00-0XA0

Used for dual IM redundancy placement of two IM153-2 to achieve redundancy 6ES7195-7HD10-0XA0

Installation precautions:

The active bus module must be installed on a dedicated DP rail (6ES7195-1xxx) and cannot use a regular S7-300 rail.