Copy RAM to ROM on Sinamics S120 via PROFINET BICO: P971 Access

Problem Summary

On a Sinamics S120 CU310-2 PN controlled by a SIMATIC S7-1500 over PROFINET with a free telegram (BICO 4/4), the PLC cannot reach parameter p0971 (Copy RAM to ROM) through the cyclic process-data image. Engineers expect to drag p0971 onto the telegram like a control word or status word and find that the parameter does not appear in the parameter list, that the slot is reported as "reserved", or that SINA_PARA_S returns an error because the request is being routed to the wrong drive object.

This is not a GSDML import error. It is the expected behavior of a free telegram: only the PZD slots you have wired in BICO are exchanged cyclically. Every parameter access that is not part of that wired PZD must travel over the PROFINET acyclic record-data channel (RPC + read/write record, sometimes called the PKW or parameter channel), and the request has to be addressed to the correct drive object — typically the Control Unit (DO 1) — not the Drive object that hosts the telegram.

Why p0971 Is Not Visible in the Free Telegram

The free telegram configuration strips the SINAMICS parameter channel from the cyclic frame. The mapping that BICO produces (4/4 means 4 words of PZD in each direction, all assigned by the user) is reduced to:

Parameters such as p0971, p0977, p0010, or p0009 are not on the BICO picker by default, and even when they are they cannot be placed in the cyclic PZD without corrupting the BICO routing. The intended way to drive them from the PLC is the acyclic parameter channel that runs in parallel with the cyclic PZD on the same PROFINET connection.

PROFINET Acyclic Parameter Access Fundamentals

The SINAMICS drive supports PROFINET acyclic services through the standard record-data read/write RPC calls (RPC handle 0xFFFE, record index 0xB02E for read, 0xB02F for write per the PROFIdrive profile, or the legacy indices 0xB02A/0xB02B). Each request encodes:

1. Drive Object number (DO) — 1 = Control Unit, 2 = first Drive, etc.
2. Parameter number — including the "p" or "r" qualifier
3. Index — array element or instance (0 for scalar parameters)
4. Subindex / attribute — value, min, max, name, text
5. Number of elements — 1 for a single value

The PLC block that wraps these primitives for SIMATIC is SINA_PARA_S. The block that wraps them and provides high-level services (Copy RAM to ROM, factory reset, firmware update trigger) is shipped in the Siemens LAcycCom library as FB 30515.

Solution Path 1: SINA_PARA_S Function Block

SINA_PARA_S (FB 287 / instance DB, supplied with the SINAMICS S120/S150 block library for S7-1500/1200) performs a single read or write of one parameter on a given drive object. The block is supplied with the SINAMICS S120/S150 DriveLib — install it from the Siemens Support portal entry 109475826 (DriveLib for S7-1500/S7-1200) and drag the FB into the project.

Block interface

Wiring for Copy RAM to ROM

To save parameters in the active drive object, write the value 1 to p0971 with DOID = 2 (Drive_1). To save parameters held in the Control Unit (for example, the device name, IP settings, or CU-level parameters that the free telegram does not touch), write the value 1 to p0971 with DOID = 1.

STATUS word decoding

Solution Path 2: LAcycCom Library FB 30515

The LAcycCom (Local Acyclic Communication) library is a Siemens-supplied package for SIMATIC that wraps SINA_PARA_S, SINA_PARA (legacy S7-300/400) and the PROFINET/DP record calls into ready-to-use service blocks. Download it from Siemens Support entry 109479553 — LAcycCom library for SIMATIC. The relevant FB is:

Inputs of FB 30515 (LAcycCom_CopyRamToRom)

The block issues a write of 1 to p0971, polls the return value (DONE / BUSY / ERROR), and only resets its own done flag once the drive has cleared the busy attribute on p0971. A successful save returns 1 in the read-back value of p0971 and the next read shows p0971 = 0 again (the drive sets the request bit to 1, copies, and resets to 0).

GSDML Import and Device Configuration

Before any acyclic block will work, the SINAMICS GSDML must be installed in TIA Portal and the drive must be present as a PROFINET device with a valid AR (Application Relationship):

1. Open TIA Portal → Options → Manage general station description files (GSD).
2. Install the SINAMICS S120 CU310-2 PN GSDML (for example GSDML-V2.34-Siemens-Sinamics_S120_CU310x_PN-20150112.xml for firmware 4.7/4.8, or the matching file for your firmware — check the drive's "About" page or the readme in the GSD download).
3. Drag the device into the topology and assign it to the S7-1500 PROFINET interface.
4. Assign a unique device name (PROFINET naming convention, no spaces, max 240 chars) and verify the IP address matches the project.
5. Verify the AR is online: the drive's port LEDs show green link + a steady ACT and the SINAMICS webserver or STARTER shows "PROFINET is connected".

Parameter Numbering: CU Object vs Drive Object

Each SINAMICS drive object has its own parameter namespace. p0971 exists on the Control Unit and on every Drive object, but each instance only saves the parameters of its own object. When a project is using a free telegram on a Drive object, the user typically wants to save the recipe associated with that drive. To also save CU-level parameters (IP, name, drive list, encoder configuration) you must write p0971 separately with DOID = 1.

If you need a one-shot save of every object (the equivalent of the STARTER "Copy RAM to ROM (all)" menu), you must issue p0971 = 1 sequentially to each DOID, and finally to DO 1. p0977 is sometimes used as a CU-side flag that triggers the global save; consult the parameter list for the firmware in question before relying on it.

Step-by-Step: Copy RAM to ROM from TIA Portal

1. Install the SINAMICS S120 DriveLib and the LAcycCom library into the TIA Portal global library. Restart TIA Portal after installation.
2. Open the PLC project and drag LAcycCom_CopyRamToRom (FB 30515) into a cyclic OB (OB1 is acceptable; OB35 at 100 ms also works for asynchronous triggers).
3. Create an instance DB (e.g. iDB_CopyRamToRom).
4. Wire the inputs:
   • ID = HW handle of the CU310-2 (right-click the device → "PROFINET IO device → PROFINET device number" or the system constant of the device).
   • DOID = 2 for the connected Drive, 1 for CU-only save.
   • TIMEOUT = T#10s (default).
5. Add a momentary pushbutton or HMI tag wired to a rising-edge flag that sets REQ. The block latches until DONE or ERROR; it will not retrigger on a held input.
6. Compile, download, and go online. Trigger the HMI button. Watch the SINAMICS display — the drive should show "Busy" for 1–8 seconds, then return to "Ready". The flash LED on the CU310-2 flickers during the write.
7. Verify by powering the CU310-2 off and on. The saved parameters are now persistent.

Error Codes and Diagnostics

Verification Procedure

1. After the block reports DONE = 1 and ERROR = 0, read p0971 back with SINA_PARA_S in read mode. The expected value is 0 (the drive clears the trigger after the copy).
2. Read a parameter that was recently changed at runtime, e.g. p1120 (ramp-up time). Confirm it matches the HMI value sent during the last ramp-up.
3. Power-cycle the CU310-2 PN. After the drive returns to "Ready", verify the same parameter still has the new value.
4. On a separate project step, deliberately change a parameter, do not trigger the copy, power-cycle, and confirm the parameter reverted. This proves that you are seeing the saved set and not just RAM.
5. For CU-level saves, change the PROFINET device name in the expert list, trigger a copy with DOID = 1, power-cycle, and confirm the name is preserved.

Edge Cases and Field Caveats

• Free telegram + Standard telegram conflict. If the GSDML is updated and the drive is changed from a Standard telegram 1/1 to a free 4/4, the BICO interconnects on the previous telegram are lost. Re-wire the BICO after the switch; the acyclic p0971 calls are independent of the telegram and remain valid.
• Multiple users on the same drive. Only one PKW job at a time per drive is reliable. LAcycCom serialises its own calls, but if STARTER is online at the same time it will block writes (0x80CF). Disconnect the commissioning tool before triggering copies from the PLC.
• Save-during-operation. Some parameters cannot be saved while the drive is in state r0002 > 1. The block will return 0x80CE. Stop the drive, copy, then re-enable.
• Replacing the CF card or SD card. Copy RAM to ROM writes to the non-volatile memory of the CU310-2, not to a removable card on the CU310-2 itself. If the system uses a SIMOTION-style external card on a different DO, the save target is the local flash of that DO.
• Firmware mismatch. The LAcycCom FB list above applies to library version ≥ V4.0. For older library versions the block numbers may differ. Always check the "About" tab of the library and the associated readme, which is shipped in the same ZIP as entry 109479553.
• Cyclic p0971 via BICO. It is technically possible to route a free telegram word to CI: p0971, but doing so defeats the safety of the acyclic channel: the save runs every cycle while the bit is high, and the save can take longer than the PROFINET cycle time, leading to overlapping jobs and bus errors. Always use SINA_PARA_S or LAcycCom.