Configuring SINAMICS PM250 Free Telegram PROFIBUS P2071

Overview

The SINAMICS PM250 (CU250S-2DP Vector) drives support a "free telegram" configuration on PROFIBUS that lets you assemble the receive and process data words (PZDs) individually rather than locking the drive to a predefined Siemens standard telegram. When the drive is set to p0922 = 999, the firmware stops interpreting the cyclic payload as a fixed Standard Telegram 1, 2, 3, 4, 5, 6, 7, 9, 110, or 111, and treats the configured PZD set as raw words that the controller can map as needed. The S7-315-2DP master exchanges these PZDs using the SIEM8170.gsd or equivalent GSD for the CU250S-2DP.

For S7-315-2DP commissioning, the central question is what p2071 actually controls, whether it must be set to the length of the status word, and how the Safety Information Channel / Safety Control Channel (SIC/SCC, telegrams 700–706) is positioned in the free PZD layout. The Status Word (ZSW1) is always exactly 1 word (16 bits) when emitted from the drive; the parameter p2071 is not a length field for the status word, it is the start offset of the SIC/SCC telegram inside the free telegram payload. The free telegram still contains a ZSW1 at its standard position unless you re-arrange it via interconnect parameters, but the safety channel occupies a different indexed slot identified by p2071.

Prerequisites

Before commissioning the SINAMICS PM250 with free PROFIBUS telegram and S7-315-2DP, confirm the following:

• SINAMICS PM250 with CU250S-2DP Vector Control Unit (6SL3225-0BE32-2UA0 series or equivalent), firmware ≥ 4.7. Recommended baseline: firmware 4.7 SP3 or 4.8 for full compatibility with STARTER V5.4 and Startdrive V15.1.
• SIMATIC S7-315-2DP (6ES7315-2AG10-0AB0 or later) with STEP 7 V5.5 SP4 / SP5 installed.
• STARTER commissioning tool V5.4 SP1 or higher, with the matching drive ES package installed so the CU250S-2DP appears in the device catalog.
• PROFIBUS DP cable (6XV1830-0EH10 or compatible), PROFIBUS connectors with termination switch, and bus terminators enabled at both physical ends.
• GSD file SIEM8170.GSE (CU250S-2DP) loaded into the STEP 7 hardware catalog.
• PLC program blocks: OB1 (cyclic), OB82 (diagnostic), OB86 (rack failure), and the standard drive function blocks FB2/FB3 (PZD receive/send) or custom data handling.
• Optional: Safety license for SIC/SCC, only if Safety Integrated is required.

PROFIBUS Telegram Model for SINAMICS PM250

SINAMICS drives on PROFIBUS DP-V1/V2 use the PPO (Parameter-Process-Data-Object) or PZD-only model. The CU250S-2DP supports the following PZD layouts:

When you choose p0922 = 999, STARTER (or the Starter offline configuration) shows a tabular editor where you assign each PZD slot to a connector input (BICO source) on the receive side and to a connector output on the send side. The total length of this free telegram is what is propagated to the S7-315-2DP via the GSD when the drive is inserted in HW Config.

Parameter Map: p0922, p2079, p2070, p2071

The four parameters control the cyclic PZD structure. They are interdependent, and mis-configuring them is the most common cause of F08501 (sign-of-life failure) or F08502 (PZD configuration error) faults.

Step-by-Step: Configuring Free Telegram with p2071

1. Open STARTER and connect to CU250S-2DP. Go online, then navigate to Drive → Communication → PROFIBUS. Verify p0922 is currently a fixed value (e.g. 1) or already 999.
2. Open the Telegram Configuration. In STARTER, double-click Configuration → Telegram configuration. The dialog lists p0922 and p2079 at the top.
3. Select free telegram. Change p0922 to 999. The receive and send PZD tables unlock to allow BICO source/target selection for each word. For example, for a 10-word send telegram you can set: PZD1 = ZSW1, PZD2 = NIST (actual speed), PZD3 = IA (actual current), PZD4 = Udc (DC-link voltage), PZD5–PZD10 = additional connectors you wire via BICO.
4. Verify the total PZD count. Count the number of PZDs you have placed in the send (drive → PLC) table. Suppose the layout is 10 words. The SIC/SCC safety words will be appended after these 10 words if Safety Integrated is enabled and configured. In that case, p2071 should be set to 10, meaning the safety channel starts at offset 10 (the 11th word). If Safety Integrated is NOT used, leave p2071 at its default (typically 0) or do not change it; setting it to a non-zero value when no SIC/SCC telegram is configured has no functional effect because the safety channel is not populated.
5. Configure SIC/SCC only if Safety Integrated is active. Navigate to Functions → Safety Integrated. Enable the safety functions (STO, SS1, SBC, SLS as required). The drive will then publish a Telegram 70x. Set p2071 (send direction) and p2070 (receive direction) to the offset where the safety words are placed within your free telegram.
6. Save and copy RAM to ROM. Click Copy RAM to ROM in STARTER so the configuration survives a power cycle. Then perform a power-on reset or issue p0977 = 1 for parameter save.
7. Update the STEP 7 HW Config. Open SIMATIC Manager, open the S7-300 station, and double-click the DP master system. Right-click the CU250S-2DP slave, choose Object Properties → Telegram Configuration. STEP 7 reads the telegram length from the GSD. If you changed p0922 to 999 after the slave was inserted, you must re-insert the slave or click Update Catalog so HW Config re-reads the configured PZD length.
8. Map the PZDs to I/O addresses. HW Config will assign peripheral addresses (e.g. PE 256…275 for inputs, PA 256…275 for outputs). Use these in the STEP 7 program via L PIW 256 for the status word, or via FB2 (PZD receive) and FB3 (PZD send) standard blocks.
9. Download the hardware configuration to the S7-315-2DP. Then run a CPU restart to clear the OB82/OB86 diagnostics.

BICO Source and Target Interconnections for Free Telegram

In free telegram mode, the drive does not automatically route ZSW1, ZSW2, NIST, IA, MIST, UIST, etc., to specific PZD slots. You must wire each PZD slot to a connector. The relevant interconnection parameters are p2050, p2051, p2061, and p2062 (send direction), and p2050 is read for receive. Below is a typical 10-word free send telegram with SIC/SCC at offset 10:

On the receive side, p2051[0] typically defaults to r2090.0 for STW1. For free telegram you can route any PZD slot to any binector input via p2051 and subsequent index parameters.

Status Word and Control Word in Free Telegram

The Control Word (STW1) and Status Word (ZSW1) are mandatory in the first two PZD slots of any PROFIdrive-compliant PZD set when the drive is operated in a standard control mode. In free telegram (p0922 = 999), this default is enforced by the PROFIdrive profile: if the drive detects STW1 / ZSW1 are not in the first two slots, it generates fault F08501 "Sign-of-life failure" or F08502 "PZD configuration error" within 2 × p2047 (sign-of-life monitoring time, default 0.5 s, so within ~1 s).

The user-defined 10 words in the original question (ZSW1 + ZSW2 + current + voltage + ...) is interpreted as: PZD1 = ZSW1, PZD2 = ZSW2 or NIST_A, and PZD3–PZD10 = whatever connectors the application requires. The "10" the user mentioned refers to the total PZD count, not the bit length of the status word. Each status word is exactly 16 bits (1 word) in PROFIdrive.

Verification and Diagnostics

1. Check r2050 and r2051 indexing. In STARTER expert list, view r2050[0..9] and r2051[0..9]. Each entry shows the currently active BICO source / target. If a value is 0, the slot is unconnected.
2. Check p2070 and p2071 in the expert list. Verify p2071 equals the offset where the safety channel is expected. If the application has no safety channel, p2071 can be left at 0 (default).
3. Read r2054 (PZD diagnostics). STARTER's Communication → Telegram diagnostics shows the active telegram (p0922) and the cyclic configuration. It also displays the PROFIBUS PZD count as recognized by the drive.
4. Monitor r0046 (missing enable / fault code). If the drive refuses to enter Run mode and r0046 shows F08501 or F08502, the free telegram configuration does not match the S7-315-2DP's PZD length. The most common cause: STEP 7 HW Config still has a different telegram length (e.g. 6 words from Telegram 3) than the drive (10 words). Re-insert the slave with the new GSD PZD count.
5. Check PLC online I/O view. In STEP 7, open the drive's PZD inputs (PIW) and outputs (PQW) and verify that the bit pattern in PIW 256 matches the expected ZSW1 bits (e.g. bit 02 = operation enabled, bit 06 = switch-on inhibited, bit 11 = warning active).
6. Trigger STO test (if Safety Integrated active). With safety channel present at offset p2071, force the safety request via terminal or via PROFIsafe and verify F01611 (Safety function requested) is logged, the drive outputs are de-energized within p9651 (STO debounce, default 250 ms), and the safety status word reflects the state to the PLC.
7. Confirm sign-of-life. The drive sends a 4-bit sign-of-life counter (ZSW1 bits 12–15) which the PLC must echo back in STW1 bits 12–15. Mismatching counters within 2 × p2047 trips F08501.

Troubleshooting Matrix

Interaction with Other SINAMICS Parameters

Several related parameters must be coherent when you activate a free telegram:

• p0918: PROFIBUS node address. Must be unique on the bus; default 6 for PM250.
• p0922: PROFIdrive PZD telegram selection. Set to 999 for free telegram.
• p2047: PROFIBUS sign-of-life monitoring time. Default 0.5 s. Increase to 1.0 s for slow PLC scan times (S7-315-2DP with OB1 cycle > 250 ms).
• p2050[0..15]: BICO source for send PZDs.
• p2051[0..15]: BICO target for receive PZDs.
• p2061[0..15]: Sign-of-life source (only for p0922 = 4 or 220 with sign-of-life enabled).
• p2070: SIC/SCC start offset receive (PLC → Drive).
• p2071: SIC/SCC start offset send (Drive → PLC).
• p2079: PROFIdrive PZD telegram extension. Only relevant when combining a fixed telegram with an extension.

According to the SINAMICS S120 Safety Integrated Function Manual, when the user changes the configuration from a fixed telegram to free (p0922 = 999), the numerical values stored in p2070 and p2071 are preserved from the previous configuration. Because their semantic meaning changes to "offset within the free telegram", you should re-validate them after each telegram change, especially if Safety Integrated telegrams are involved. See the official SINAMICS S120 Safety Integrated Function Manual for the full description.

Edge Cases and Field-Proven Caveats

1. Mixing free telegram with PROFIsafe on PROFIBUS. PROFIsafe uses a different mechanism (F-host address, F-source address) and adds a safety slot to PROFINET/PROFIBUS. The SIC/SCC channel is the older safety mechanism, intended for compatibility. If your application uses PROFIsafe, do not use SIC/SCC and p2071 can remain at 0.
2. Reversing PZD direction unintentionally. p2050 wires send direction. p2051 wires receive. Swapping them silently compiles the configuration in STARTER but the drive will not pass commissioning because the input/output interpretation is reversed.
3. Free telegram size limit. Maximum 16 PZDs (32 bytes) per direction on CU250S-2DP. Exceeding this triggers a configuration error at startup.
4. STARTER shows stale telegram after online change. If you edit p0922 online and STARTER does not refresh the Telegram Diagnostics view, click "Update" or close/reopen the Telegram Configuration dialog. This is a UI issue and does not affect the drive.
5. STEP 7 keeps the old I/O addresses. After a Telegram change, the I/O addresses in STEP 7 hardware config may shift. Re-validate all PIW/PQW references in the PLC program and recompile.
6. StarDrive vs. STARTER behavior. In Startdrive (TIA Portal) for S7-1500/S7-1200, the parameter numbering is the same, but the UI differs. S7-315-2DP is STEP 7 V5.x territory; use STARTER.

Parameter Summary Cheat Sheet

Verification Checklist Before Going Online

• Drive firmware version compatible with STARTER/Startdrive ES package.
• PROFIBUS address set uniquely (p0918) and matched in HW Config.
• p0922 = 999 saved to ROM and drive restarted.
• p2050[0..n] and p2051[0..n] all wired to valid BICO sources/targets.
• p2070 and p2071 set to the SIC/SCC offset, or left at 0 if no safety channel is used.
• STEP 7 HW Config I/O length matches the free telegram PZD count.
• Sign-of-life bits in STW1 (12–15) are toggled by the PLC each OB1 cycle.
• FB2/FB3 or equivalent blocks are scheduled in OB1 with the correct DB instance.
• All cabling shielded, terminated, and grounded per Siemens PROFIBUS guidelines.
• STARTER online diagnostics show no F08501/F08502 faults after the first commissioning power-up.

FAQ