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.

Hot plugging is only applicable to I/O modules, and there are restrictions on hot plugging for power and IM modules (power off or following a specific sequence).

After replacing the module, the CPU will automatically reconfigure. The 'hot plug' attribute needs to be activated in STEP 7.

Redundant system application (S7-400H)

In situations where high availability is required (such as continuous chemical production), two IM153-2 can be installed back-to-back through redundant bus modules (6ES7195-7HD10-0XA0) and paired with S7-400H redundant CPUs. In redundant mode:

Two interface modules work simultaneously, one as primary and one as backup.

The main station exchanges data with the CPU, while the backup station monitors and synchronizes the status.

When the main station fails, the backup station automatically takes over, with a very short switching time and uninterrupted process.

The configuration of the redundancy group in STEP 7 is similar to that of the regular ET 200M, and "IM153-2 Redundant" needs to be selected in the hardware directory.

HART Analog Module: Intelligent Management of Process Signals

ET 200M provides analog input/output modules that support the HART protocol, suitable for configuring and diagnosing smart instruments such as pressure transmitters and valve positioners. The HART module can only be used with IM153-2 or IM153-4 PN HF.

5.1 8AI HART（6ES7331-7TF01-0AB0）

Channel: 8 current inputs, 0/4~20 mA, HART protocol V5.0.

Performance: 16 bit resolution, Sigma Delta conversion, adjustable integration time (50/60 Hz suppression), basic conversion time of 65 ms (50 Hz).

Additional features: Supports reading of HART minor variables and firmware updates.

Diagnosis: Limit alarm, disconnection diagnosis.

Power supply: The backplane 5 V consumes 120 mA, the load voltage is L+20 mA, and provides 24 V/60 mA power supply for the two-wire transmitter.

5.2 8AO HART（6ES7332-8TF01-0AB0）

Channel: 8 current outputs, 0/4~20 mA, HART.

Performance: 16 bit resolution, basic execution time of 10 ms (analog output mode) or 50 ms (HART AO mode).

Load capacity: maximum 750 Ω, inductive load ≤ 10 mH.

Diagnosis: Short circuit, disconnection alarm.

5.3 Ex Explosion proof HART Module

Used for intrinsic safety (Ex ia) circuits, can be installed on Zone 1/2 site:

Ex AI HART (6ES7331-7TB10-0AB0): 2-channel, single channel isolation. Intrinsic safety parameters: Uo ≤ 26 V, Io ≤ 96.1 mA, Po ≤ 511 mW, Co ≤ 62 nF, Lo ≤ 3 mH. Higher accuracy, basic error ± 0.1%, full temperature ± 0.45%.

Ex AO HART (6ES7332-5TB10-0AB0): 2-channel, current output, 12 bit+symbol resolution. Intrinsic safety parameters: Uo ≤ 19 V, Io ≤ 66 mA, Po ≤ 506 mW, Co ≤ 230 nF, Lo ≤ 7.5 mH.

Engineering Tip:

HART communication is achieved through the superposition of 4-20 mA lines, without occupying any additional channels. The instrument can be accessed through a handheld terminal or upper computer via a HART modem.

In STEP 7, it is necessary to configure the "HART variable" mapping for the HART module and read the secondary variables into the process image.

SIPLUS Extreme Environment Version: -40 ° C to+70 ° C

For harsh environments such as outdoor, coastal, desert, or chemical plants, Siemens offers the SIPLUS series (order numbers starting with 6AG1). They are based on standard modules, but have undergone special coatings and protection to withstand:

Wide temperature range: Operating temperature from -40 ° C to+70 ° C (some models are limited to 60 ° C under UL/cUL or ATEX).

High altitude: up to 5000 meters, with a reduced usage required for altitudes above 2000 meters.

Chemical active substances: meet EN 60721-3-3 3C4 grade (including salt spray) and ANSI/ISA-71.04 GX grade (excluding trichloroethylene).

Bioactive substances: mold, fungal spores (3B2 grade).

Mechanically active substance: sand and dust (3S4 level).

Typical model:

SIPLUS IM153-1（6AG1153-1AA03-2XB0）

SIPLUS IM153-2 HF（6AG1153-2BA10-7XB0）

SIPLUS 8AI HART（6AG1331-7TF01-7AB0）

SIPLUS 8AO HART（6AG1332-8TF01-2AB0）

SIPLUS Ex AI HART（6AG1331-7TB00-7AB0）

Important: The backplane output current of the SIPLUS module may need to be derated above 60 ° C (e.g. IM153-4 PN HF 5 V output drops to 0.9 A at>60 ° C). When selecting, the derating calculation should be based on the ambient temperature.

Compatibility and precautions of functional modules

ET 200M supports a large number of S7-300 functional modules, but not all modules can be used for distributed I/O. The following table summarizes the applicability of key modules:

Functional module ordering number supports IM153-1, IM153-2, IM153-4 PN Remarks

FM 350-1 counter 6ES7350-1AH03-0AE0 ✓✓✓ requires STEP 7 configuration

FM 350-2 counter 6ES7350-2AH01-0AE0 ✓✓✓✓-

FM 351 positioning module 6ES7351-1AH01-0AE0 ✓✓✓✓ Fast/Slow Drive

FM 352 electronic cam 6ES7352-1AH02-0AE0 ✓✓✓-

FM 352-5 high-speed Boolean processor 6ES7352-5AH10-0AE0 ✓✓✓ requires separate configuration package

FM 355 C/S Controller 6ES7355-0VH10-0AE0 ✓✓✓ PID Control

SM 338 POS Input 6ES7338-4BC01-0AB0 ✓✓✓✓ SSI Absolute Value Encoder

Important limitations:

When using a third-party main station (not Siemens) or configuring through GSD files, some parameters of functional modules may not be fully supported. It is recommended to use STEP 7 or TIA Portal for complete configuration.

The FM 357-2 path/position control module does not support ET 200M (only for S7-300 central rack).

Some functional modules require additional configuration software packages (such as drivers for Technology CPUs).

Power supply and backplane current budget

The power supply for the ET 200M site can come from:

External 24V DC power supply directly supplies the load voltage L+of IM and I/O modules.

S7-300 power modules (such as PS 307) can also be inserted into the rack, but they occupy one I/O slot.

Backboard current calculation:

The total 5V current consumed by each module (obtained from the backplane bus of IM) must not exceed the rated output of IM. Typical value:

IM153-1：1 A

IM153-2/4 PN：1.5 A

Normal digital quantity 16DI (6ES7321-1BH02-0AA0) approximately 80 mA

Analog quantity 8AI (6ES7331-1KF02-0AB0) approximately 100 mA

The FM function module may reach over 200 mA

Voltage drop and cable: The length of PROFIBUS DP cable follows the standard (maximum 1000 m @ 93.75 kbps, 200 m @ 12 Mbps). PROFINET uses industrial Ethernet twisted pair cables with a maximum length of 100 meters per segment.

Key points of engineering configuration and diagnosis

GSD file: For non Siemens main stations, the GSD file for IM153 needs to be downloaded. The typical GSD for IM153-1 is SIEM801D.GSD, while IM153-2 is SI05801E.GSG.

STEP 7 Configuration: Insert PROFIBUS DP → ET 200M → corresponding IM in the hardware directory, and then add the I/O module. The DP address (1-125) of the IM needs to be set correctly.

Timestamp configuration: For IM153-2, it is necessary to enable "timestamp" in the module properties and specify the message cache size and trigger edge.

HART configuration: In the analog module properties, select "HART protocol" to map secondary variables to the input process image.

Diagnostic alarm: almost all modules support diagnostic alarm (such as disconnection and overrange). It is necessary to call corresponding OB 82 in CPU and write processing logic.

Hot plug setting: In STEP 7, select "Start when replacing module" for the "Hot plug" attribute of IM.

Lifecycle and spare parts strategy

Siemens official statement: SIMATIC S7-300/ET 200M series products will generally be available until 2023, followed by a discontinuation announcement and continued provision of spare parts for at least 10 years. Therefore:

It is recommended to switch to PROFINET based ET 200SP or ET 200MP systems for new projects to achieve longer product cycles.

For the existing ET 200M equipment, vulnerable parts (IM module, active bus module, special I/O module) should be inventoried and inventory should be established.

When upgrading, PROFIBUS DP can be gradually replaced with PROFINET, and IM153-4 PN can be used to be compatible with existing I/O modules, reducing the cost of transformation.

Typical troubleshooting

Possible causes and solutions for the phenomenon

IM's BF light flashes or stays on, bus communication interruption, address conflict, and terminal resistance not connected. Check the DP cable, confirm that the station address is unique, and set the terminal resistance

Unable to recognize module (SF light on) module not inserted correctly, configuration does not match reality. Reinstall the module and check if the model and order number in the hardware catalog match

After hot plugging, the module does not work and the active bus module is not used, or the configuration is not activated. Replace with an active motherboard and enable hot plugging support in STEP 7

HART variable cannot be read. The instrument supports HART but is not enabled, or the loop resistance is insufficient. Check the total loop resistance (≥ 250 Ω) and enable HART in the module properties

After redundancy switching, data loss occurs. The firmware version of the backup IM is inconsistent with the main one. Upgrade two IMs to the same firmware and check the redundancy parameters