Integrating AddFEM Front-End Modules (6DL3100-8AC00-0AA0) with FM 458-1 DP in SIMATIC PCS 7 - PROFIBUS DP and Function Block Engineering

Integrating the SIMATIC AddFEM front-end module (6DL3100-8AC00-0AA0) with an FM 458-1 DP application module (6DD1607-0AA2) in a SIMATIC PCS 7 automation rack requires establishing a high-speed PROFIBUS DP master-slave link and deploying specialized D7-SYS function blocks. The AddFEM module acts as a fast distributed I/O peripheral connected to the onboard PROFIBUS DP interface of the FM 458-1 DP. In the CFC engineering environment (using D7-SYS), analog inputs and high-speed counter values are acquired using dedicated AddFEM library blocks: AF_AI for analog inputs, AF_CNT for frequency and counter channels, and AF_DP for communication synchronization. Additional function block libraries are imported into the FM 458 environment via the CFC Options -> Block Types dialog.

High-Performance Architecture: AddFEM and the FM 458-1 DP Co-Processor

In highly demanding process automation sectors—such as turbine governor control, rolling mill drives, and excitation systems—standard S7-400 execution cycle times (10ms to 100ms) are insufficient. To achieve sub-millisecond control, Siemens deploys the FM 458-1 DP application module (6DD1607-0AA2) programmed via D7-SYS in CFC, paired with the AddFEM (Additional Front-End Module 6DL3100-8AC00-0AA0).

The AddFEM is a ruggedized, high-speed front-end module featuring 8 high-precision analog inputs (supporting 100 kHz sampling), 4 high-speed counter inputs (up to 500 kHz), and fast digital channels. Rather than communicating through the slower S7-400 P-bus backplane, the AddFEM connects directly to the dedicated PROFIBUS DP master port of the FM 458-1 DP at 12 Mbit/s, enabling deterministic microsecond-level closed-loop sampling.

Hardware Configuration and PROFIBUS DP Linkage

Configuring the communication pipeline between the FM 458-1 DP and the AddFEM requires precise HW Config steps:

S7-400 Rack Configuration: Insert the FM 458-1 DP into an available subrack slot in HW Config.
PROFIBUS Master System: Configure the onboard DP interface of the FM 458-1 DP as a PROFIBUS DP Master. Assign a dedicated subnet isolated from the main plant bus.
AddFEM Slave Insertion: From the hardware catalog (PROFIBUS DP -> Additional Field Devices -> I/O -> AddFEM), drag the AddFEM (6DL3100-8AC00-0AA0) onto the FM 458 DP master string.
I/O Addressing: Parameterize the DP slave address (set via DIP switches on the physical AddFEM module) and configure the consistent input/output word addresses in HW Config.

Function Block Assignment for Analog Inputs and Counters (AF_AI, AF_CNT, AF_DP)

Programming the FM 458-1 DP is executed using D7-SYS within the CFC Editor. Engineers must utilize the specialized AddFEM function block library rather than standard S7 or APL blocks:

Function Block NamePurpose / Technical RoleKey Parameters / Output InterfacesAF_DPCommunication Driver and Status HandlerManages DP communication, diagnostic interrupt evaluation, and cycle syncAF_AIAnalog Input Acquisition and ScalingCH_NO (Channel 1-8), RAW_VAL (Raw integer), VAL (Scaled real value)AF_CNTHigh-Speed Counter and Frequency MeasurementMODE (Period/Count/Frequency), COUNT (Current pulses), FREQ (Hz)AF_DI / AF_DOFast Digital Input / Output ProcessingSub-millisecond digital interlocks and valve pulsing

Importing Libraries into FM 458 CFC:

To add extra block libraries to your FM 458 project:
1. Open the CFC chart for the FM 458-1 DP.
2. Select Options -> Block Types from the menu.
3. In the left-hand pane ('Installed Libraries'), locate the AddFEM or custom D7-SYS library.
4. Select the required blocks (AF_AI, AF_CNT, AF_DP) and click -> to import them into the project block folder on the right.

Verification

Verify AddFEM hardware communication and signal processing using these diagnostic procedures:

LED Status Inspection: On the AddFEM front panel, verify that the RUN LED illuminates solid green and the BF (Bus Fault) LED is completely unlit.
CFC Online Test: Open the FM 458 CFC chart in online test mode (Test -> Open). Inspect the AF_DP block output STATUS (must equal 16#0000).
Counter Signal Verification: Connect a pulse generator to the AddFEM counter input. Observe AF_CNT.COUNT and AF_CNT.FREQ updating smoothly in real-time.

Limitations and Operational Precautions

When integrating AddFEM modules with FM 458 co-processors, adhere to these constraints:

PROFIBUS Cable Shielding: Due to the ultra-high sampling rates (12 Mbit/s) and fast signal edges, PROFIBUS cables must use 360-degree shield bonding and proper terminal resistor termination at both physical ends.
D7-SYS Engineering Licenses: Programming the FM 458-1 DP requires a valid D7-SYS software license in Automation License Manager (ALM) on the Engineering Station.
Commercial Procurement and Licensing Disclaimer: The AddFEM module (6DL3100-8AC00-0AA0) and FM 458-1 DP (6DD1607-0AA2) are specialized motion/turbine hardware products. Always confirm hardware availability, spare parts status, and exact MLFBs with an authorized Siemens distributor before designing critical process architectures.

Engineer FAQ

Can the AddFEM module communicate directly with an S7-400 CPU without FM 458?

Yes. The AddFEM can connect directly as a standard PROFIBUS DP slave to a CPU 414 or CPU 410 onboard port; however, execution cycle times will be limited to standard S7 cyclic interrupt speeds (e.g., 10ms-100ms) rather than the sub-millisecond speeds of FM 458.

How do I transfer acquired AddFEM data from the FM 458 to the S7-400 CPU?

Data exchange between the FM 458 and the host S7-400 CPU occurs across the high-speed P-bus backplane using communication blocks COM_CP / COM_CPU or shared communication RAM areas configured in HW Config.