Extracting and Automating I-O Channel Types in PCS 7 Import-Export Assistant (IEA)

In SIMATIC PCS 7 Import-Export Assistant (IEA), automatically determining whether an instrumentation signal is a Digital Input (DI), Digital Output (DO), Analog Input (AI), or Analog Output (AO) from an exported .IEA file requires configuring the Process Tag Type (PTT) to export the underlying channel driver Block Type or inspecting address prefix syntax. While the standard signal "Value" column in an .IEA file only exports raw addresses (e.g., 16#... for input words IW), adding the block type parameter (PCS7DiIn, PCS7DiOu, PCS7AnIn, PCS7AnOu) or a standardized user attribute to the Process Tag Type template exposes explicit channel typing, enabling external scripts to automate I/O module allocation.

Process Tag Types (PTT) and IEA File Architecture

In large-scale PCS 7 engineering, the Import-Export Assistant (IEA) automates the replication of standardized process control loops (motors, valves, transmitters) from master templates known as Process Tag Types (PTT).

Engineers frequently develop external Python, C#, or Excel tools to process customer instrumentation schedules, calculate total I/O module counts, and pre-assign rack addresses into an .IEA file before importing the tags into SIMATIC Manager.

However, when exporting a baseline .IEA file from a PTT, engineers discover that the generated text file lists parameter paths and raw address values (such as 16#0200), but does not provide an explicit column stating whether a signal is a digital input, analog input, or output.

Why the Default IEA Export Omits Explicit Signal Direction

The .IEA file format is a tab-delimited or comma-separated table structured around PTT parameters:

Column in Default .IEAExample DataInformation ConveyedAmbiguity for External ProgramsChart NameFIT_101Name of generated CFC chartNoneSignal PathPcs7AnIn\PV_InBlock instance and pin nameRequires external lookup table to determine typeSignal ValueIW 512 (or 16#0200)Hardware peripheral addressHex format obscures module typeBlock Type (Optional)PCS7AnInNative APL block type nameExplicit: AI Channel DriverUser Comment4-20mA FlowFree engineering textNon-standardized; varies by author

Because IEA treats signals as generic pointers to peripheral memory, the export engine only outputs the columns that were explicitly flagged for export in the Process Tag Type editor.

Configuring PTT Templates to Export Driver Block Types

To ensure that exported .IEA files contain unambiguous I/O type indicators for external automation software:

Open the master Process Tag Type (.PTT) chart in the Master Data Library.
In CFC Editor, navigate to Options -> Process Tag Type -> Edit Process Tag Type....
In the parameter selection dialog, expand the channel driver block:
- For analog input: Select Pcs7AnIn -> add Block Type to the exported parameter list.
- For digital output: Select Pcs7DiOu -> add Block Type to the exported parameter list.
Alternatively, assign a standardized User Attribute or Chart Comment parameter:
- Parameterize an internal string attribute (e.g., Signal_Type = "AI_4-20mA" or "DO_24V").
Click OK to save the PTT template.
When you re-export via IEA -> Export, the resulting file will contain an explicit BlockType column identifying PCS7AnIn (AI), PCS7AnOu (AO), PCS7DiIn (DI), or PCS7DiOu (DO).

Parsing Address Prefixes in External Sizing Programs

If existing PTT templates cannot be modified, external software programs can determine signal direction by parsing standard Siemens STEP 7 address syntax:

Digital Inputs (DI): Prefixed with I (Input) or German E (Eingang), followed by byte and bit: e.g., I 10.0, E 4.2.
Digital Outputs (DO): Prefixed with Q (Output) or German A (Ausgang), followed by byte and bit: e.g., Q 12.0, A 6.1.
Analog Inputs (AI): Prefixed with IW (Input Word), PIW (Peripheral Input Word), or German PEW: e.g., IW 512, PEW 256, or hex formatted as 16#0200.
Analog Outputs (AO): Prefixed with QW (Output Word), PQW (Peripheral Output Word), or German PAW: e.g., QW 256, PAW 512.

Verification

To verify IEA export and import workflows:
1. Export a Process Tag Type using the modified template containing BlockType.
2. Open the .IEA file in a text editor or Excel; verify that every signal row clearly states its driver type (PCS7DiIn, PCS7AnIn).
3. Run the external sizing program to calculate total DI, DO, AI, and AO module counts; cross-reference against the plant equipment schedule.
4. Re-import the populated .IEA file into SIMATIC Manager; verify that all CFC charts instantiate with correct I/O addresses and zero import syntax errors.

Limitations and Operational Precautions

Ensure that address assignments generated by external tools do not overlap existing process image partitions or communication buffers. When assigning addresses in .IEA files, adhere strictly to the module address boundaries defined in Hardware Configuration: assigning an analog input to an address outside the CPU process image partition will require peripheral addressing (PEW) rather than process image inputs (IW).

Engineer FAQ

Can IEA automatically create Hardware Configuration racks?

No. IEA generates CFC charts and assigns addresses to existing hardware. Hardware racks and I/O cards must be created in HW Config (or via AdvES/PAA) before IEA import.

What file formats are supported by Import-Export Assistant?

IEA supports tab-delimited text (.txt), comma-separated values (.csv), and native .iea file formats.

How does IEA handle multi-signal blocks like MotL?

A MotL PTT typically contains multiple sub-driver blocks: Pcs7DiIn for run feedback (FbkRun), Pcs7DiIn for electrical fault, and Pcs7DiOu for start command (Start), each exported as individual signal rows.