Siemens SIMATIC ET 200M Selection

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