SINAMICS DCC P1070 Speed Setpoint and r21600 Parameter Mapping

1. Problem Context and Article Scope

A SINAMICS drive (S120, G120, G120C, G130, G150, S150) frequently receives its speed setpoint from a Drive Control Chart (DCC) block diagram rather than from an analog input, fixed setpoint, or fieldbus PZD word. In the expert parameter list the user sees two distinct entries that describe the same signal path:

• p1070[0] — the standard BiCo input "Main setpoint" of the closed-loop speed control.
• r21600 — a parameter whose number lies in the 21500… range and therefore is automatically created by a DCC chart.

This reference explains how those two parameters relate, why the DCC output carries a number beginning at 21600, and how to choose between the four possible connector types when editing block comments in the DCC editor (a component of STARTER and Startdrive). The goal is a deterministic signal path from a calculated DCC variable to the drive’s speed controller with full visibility in the expert list and full interconnectability through BiCo.

2. SINAMICS BiCo Signal Architecture in Brief

Every SINAMICS drive uses a uniform signal-routing model in which a connector (16-bit or 32-bit normalized value), a binector (Boolean), or a drive BiCo (drive-internal, normalized value with sign and unit) is sourced from a parameter named rxxxx (read-only / signal source) and consumed at a parameter named pxxxx (writable / signal sink). The interconnection is performed in the expert list by setting the sink parameter to the index of the source parameter, or graphically in the commissioning tool.

The speed setpoint channel of SINAMICS comprises a cascade of normalized connectors. The most important sink of the "setpoint from automation" cascade is CI: p1070 — the main speed setpoint input to the speed controller (r1501 is the active setpoint after ramp-function generator).

3. P1070 Main Setpoint, Detailed

p1070[0] is a connector input (CI) that accepts a normalized speed setpoint in percent of rated speed (4000 hex = 100 %). Index 0 is the standard source for the closed-loop speed control; index 1 is reserved for the supplementary setpoint that is added to the main setpoint in p1101 arithmetic.

When a DCC chart is the source, the value entered into p1070[0] is the index of the DCC-generated connector output — for example p1070[0] = 21600 sources the setpoint from r21600.

4. Drive Control Chart (DCC) Recap

DCC is a graphical, signal-flow programming environment embedded in the SINAMICS firmware (option S00/S02 for S120, available on G120 with CU250S and on S150). The chart consists of blocks (add, multiply, integrator, NSW numerical switch, limiters, filters, controllers, function generators, etc.) placed on sheets; each block has typed inputs on its left edge and outputs on its right edge. The chart is processed in the drive’s task system at one of the configured sampling times (commonly 4 ms for technology blocks on S120, 8 ms on G120 CU250S-2).

5. Connector Annotation: @ vs @*

When the DCC chart author wants to expose a block input or output to the rest of the drive system — for monitoring, for parameterisation from the HMI/PLC, or for BiCo interconnection to a standard parameter such as p1070 — they place a connector comment on the respective block pin. Two annotation prefixes are available, and the choice determines whether the resulting parameter is a normal setting parameter or a full BiCo parameter.

Examples that follow the conventions used in the supplied chart:

• @*100 Output signal — creates BiCo parameter 21600 ("Output signal"). This is the parameter seen as r21600 in the expert list.
• @50 MyStaticValue — creates a non-BiCo setting parameter 21550 that the user can write from the expert list, the PLC, or the HMI but that cannot receive a BiCo interconnection.

6. The Four Connector Combinations

Every DCC block pin is either an input or an output. Combined with the two annotation prefixes, this yields four distinct exposed-parameter types. The DCC programmer is responsible for selecting the correct one; the wrong choice leads to "parameters that exist but cannot be interconnected" or "parameters that cannot be observed".

7. The 21500 Parameter-Number Offset

All DCC-exposed parameters are mapped into the SINAMICS parameter space starting at index 21500. The number typed in the pin comment is added to this offset to produce the absolute SINAMICS parameter number. The rule is:

absolute_parameter_number = 21500 + n (where n is the integer typed after the @ or @* in the pin comment)

Parameter numbers from 21500 to 32767 are available for DCC; the practical range used in a single chart rarely exceeds 200 entries. The numbering is local to the chart and is assigned when the chart is compiled; collisions across multiple DCC charts loaded on the same drive are detected at compile time and generate a firmware reject (Fxxxxx alarm with fault value 80800… range — see Section 11).

8. Tracing the Speed Setpoint from DCC to p1070

The diagnostic flow used when a DCC-driven speed setpoint is suspect is shown in the sequence below. The same procedure identifies any DCC-to-BiCo interconnection, not only p1070.

1. Open STARTER / Startdrive, go online with the drive, switch to the Expert list.
2. Navigate to p1070[0]. Confirm the current value reads 21600 (or the index of the DCC connector). If it reads 0, the BiCo is not connected.
3. Navigate to r21600. Observe the value; it is updated on every DCC task tick.
4. Right-click r21600 → Go to DCC chart (in STARTER the function is "Signal traceback" / "BICO signal trace"). The compiler places the cursor on the DCC block output that carries @*100 Output signal.
5. Examine the upstream blocks (NSW = numerical switch in the supplied example). The I input of NSW determines which of I0 or I1 is routed to the output. The active branch should produce the expected normalized speed (100 % ≡ 4000 hex ≡ rated speed).
6. Verify scaling at p1071[0] (default 1.0) and check the ramp-function generator setpoints p1120 / p1121 for ramp-up and ramp-down times.
7. Trace forward from r1077 (setpoint after scaling) and r1078 (setpoint after ramp) into the speed controller. A divergence between r1077 and the DCC source points to a scaling problem; a divergence between r1078 and the motor speed r0061 points to a ramp or controller issue.

9. Creating and Editing DCC Connectors

The procedure to add a new BiCo output to a DCC block:

1. In the DCC editor, double-click the block pin (input or output) you wish to expose. The pin-properties dialog opens.
2. Open the Comment field and enter the annotation. The two required pieces of information are the prefix (@ or @*) and the local number. The descriptive text after the number becomes the parameter name in the expert list.
3. Examples:

   @*100 Output signal           ! creates r21600 (BiCo source)
   @101 Static setpoint [rpm]    ! creates p21601 (read/write, no BiCo)
   @*102 Actual speed feedback   ! creates r21602 (BiCo source)

4. Compile the chart. Any collision (duplicate absolute number, reserved range) is reported as a compile error.
5. Load to the drive (RAM, then ROM/persistent with "Copy RAM to ROM").
6. Confirm the parameter is visible: in the expert list filter, search for "21600" (without the leading r/p). The new entry will appear under the same name as the descriptive text typed in the comment.

10. Identification of Parameter Type at a Glance

Given a parameter in the 21500… range, the four attributes listed in the table below are sufficient to identify its role unambiguously. None of them requires opening the DCC editor.

Therefore: in the original chart, r21600 is a BiCo output (created by @*100), connectable to any CI in the drive, and is wired by the chart author to CI: p1070[0] as the main speed setpoint source.

11. Commissioning and Verification Checklist

Before releasing a DCC-driven speed setpoint to production, perform the following functional checks. They cover signal presence, polarity, scaling, ramp integration, and BiCo integrity.

12. Troubleshooting Matrix

The matrix below covers the most common incidents when a DCC speed setpoint is not behaving as expected. Each row contains the symptom, the most likely cause, and the corrective action.

13. Worked Example: DCC Speed Setpoint with Manual/Automatic Switchover

A common pattern in industry is to alternate between a manual jog setpoint and an automatic controller setpoint. The chart below is a textual representation of the graph that gives rise to r21600.

        +-----------+        +-----------+        +---------+
PI_CTRL | Y_out [%] |--+---->|NSW.I0     |        |         |
        +-----------+  |     |  NSW      |---> Y ->| limiter |---> r21600
                     |     |           |        |  +/-100% |
JOG_RPM  @*1 0 [%]  -+-> I1|           |        +---------+
                     |     +-----------+
                     |              ^
                     |              |
                     +------<-------+I  (digital selector: AUTO / JOG)

Notice that the jog input uses @*1 — a BiCo input — so that the value can be sourced from any drive signal (an analog input, a PZD word, or a static setting). The controller output is a standard block output, internally fanned out to NSW.I0 without the need for an @ annotation. Only the final chart output carries @*100 Output signal, creating the BiCo source r21600.

14. Frequently Asked Questions