Reading Bit Values with SINA_PARA FB286/FB287 in TIA Portal

Reading Bit Values with SINA_PARA FB286/FB287 in TIA Portal

Overview: SINA_PARA and SINAMICS Parameter Access

SINA_PARA is the Siemens application interface used to read and write individual SINAMICS drive parameters from a SIMATIC controller over PROFIBUS, PROFINET, or a direct internal backplane connection. It maps the cyclical acyclic parameter channel of the drive onto a structured function block interface, so that the PLC programmer does not have to handle DPV1 read/write request/response mechanics manually. The block ships in two variants:

Both blocks exist in three separate library variants supplied by Siemens: one for S7-300/S7-400 (used with STEP 7 V5.x or TIA Portal with compatible S7-300/400 targets), one for S7-1200, and one for S7-1500. The data structures and pin names are identical across targets, but the underlying call wrappers differ. The official Siemens FAQ documents the multi-parameter block under "How to read or write multiple parameters using FB286" and the single-parameter block under "How to read or write a single parameter using FB287".

Block Architecture and I/O Pins

FB286 declares an INPUT structure called Para of the data type SINA_PARA_PARAM, an OUTPUT structure called ParaOut of the same type (echoes the input after the call), and the standard job-control pins listed below.

FB287 has the same interface but NumberOfPara is fixed to 1, and the parameter structure is called Parameter with a ValueRead / ValueToWrite split for clarity.

SINAMICS Parameter Data Types and the srValue / sdValue Decision

SINAMICS exposes every parameter with a BICO datatype. The two data types engineers encounter most often when reading bits are:

The Siemens documentation quoted from the function block internals states:

"All of the parameters of the type DWORD or DINT must be written in the Parameter[x].sdValue field. The block logic automatically detects the DWORD / DINT format, and the Parameter[x].sdValue job field is used for writing or reading. For all other parameters, the Parameter[x].srValue field is used."

That decision is internal and is not driven by the programmer. The engineer's job is to read the parameter's declared datatype from the SINAMICS Parameter Manual (LH1 or FW version) and then pick the right PLC variable width to hold the result.

The r52.13 Example: Reading a Single Status Bit

Parameter r52 is the Status Word 1 of a SINAMICS drive. It is 16 bits long and exposed with the SINAMICS datatype Unsigned16. Bit 13 in many firmware revisions is mapped to "Motor overtemperature alarm" (the exact bit meaning is drive-specific; verify against the active SINAMICS List Manual for your firmware). The bit notation r52.13 is display notation only; on the wire, the drive returns the entire word r52 as a 16-bit integer.

Step 1 - Build the request

1. Create a global data block (e.g. DB_SinaPara) of type SINA_PARA_PARAM (or one that contains an array of 16 of these).
2. Set siParaNo := 52.
3. Set siIndex := 0 (no sub-index; if your parameter has one, set it to the required value).
4. Set syType := 0 (type not forced; the block reads the declared type from the drive).
5. Leave srValue and sdValue cleared for a read job.

Step 2 - Trigger the job

Provide a one-shot rising edge on the Start input of FB286 or FB287.

Step 3 - Wait for Done

When the call returns Done = TRUE without Error = TRUE, the result is in ParaOut[1].srValue as a 16-bit unsigned integer cast to REAL.

Step 4 - Convert and extract the bit

The conversion is the most error-prone step. The srValue field of SINA_PARA_PARAM is declared REAL, but the bit pattern stored in it is the 16-bit integer returned by the drive. Two field-proven ways to extract bit 13 are shown below.

Method A: Word cast and bit test (SCL)

// Read job for r52
#Para[1].siParaNo := 52;
#Para[1].siIndex  := 0;
#Para[1].syType   := 0;

IF #Start AND NOT #Busy THEN
    #StartTrig := TRUE;
END_IF;

// FB287 call (single parameter)
FB287_DB(siParaNo      := #Para[1].siParaNo,
        siIndex       := #Para[1].siIndex,
        syType        := #Para[1].syType,
        srValue       := 0.0,
        ReadWrite     := FALSE,
        Start         := #StartTrig,
        Done          => #bDone,
        Busy          => #bBusy,
        Error         => #bError,
        StatusID      => #wStatusID,
        ValueRead     => #ParaOut[1].srValue);

// Extract bit 13 of r52 from the result
// r52 is Unsigned16, so the 16-bit value lives in the low word of srValue
#StatusWord_52 := WORD_TO_INT(SHR(REAL_TO_DWORD(#ParaOut[1].srValue), 16));
#MotorOvertempAlarm_52_13 := (#StatusWord_52 AND 16#2000) <> 0;

The mask 16#2000 equals 2^13 = 8192, so the result is TRUE when bit 13 of r52 is high.

Method B: AT overlay on a DWORD

// Interpret the REAL storage as DWORD without changing the type
overlayData AT %DB100 : STRUCT
    srValueRaw   : DWORD;    // physical bits of the REAL
END_STRUCT;

// Read returns; use bit address
#MotorOvertempAlarm_52_13 := %DB100.srValueRaw.X13;

Method A is portable across TIA Portal versions; Method B is faster at runtime and easier to read in trending, but it requires the user to know that the parameter is 16 bits wide and will occupy the upper or lower 16 bits of the 32-bit REAL storage depending on the platform. On S7-1500 the conversion is to a DWORD via REAL_TO_DWORD, then shifted right by 16 to obtain the actual 16-bit parameter value before the AND-mask is applied.

Why You Cannot Read a Single Bit Directly

SINAMICS does not support a true bit-level PROFIdrive request. Every Read job returns the full 16- or 32-bit value of the parameter, and the drive resolves the index field only as a sub-index, not as a bit selector. To work around this in the PLC you have two options:

1. Read the parent word once, extract many bits. If you need r52.0, r52.13, and r52.14, call SINA_PARA once with siParaNo = 52, then use AND-mask bit tests on the result. This is the lowest-overhead approach and matches the original question.
2. Use p2099 / p2051 BICO routing to expose the bit as a separate word on the cyclical process data. The bit then arrives in the cyclical I/O image every few milliseconds without any SINA_PARA call at all, at the cost of a configurable bit in the SINAMICS telegram. This is the right answer for very fast (<10 ms) alarm reactions.

Library Versions and TIA Portal Compatibility

Always check the library's revision counter after installation. FB286/FB287 in older libraries do not support DriveObjectNo and may produce a StatusID = 16#0001 ("invalid parameter number") when pointed at a non-Control Unit object. The latest library is available on Siemens Industry Online Support under entry ID 109475973 (FB286) and 109475970 (FB287).

Reading Control/Status Words Without SINA_PARA

For the most common 16-bit words (Status Word 1 = r52, Status Word 2 = r53, Control Word 1 = r54, etc.), do not use SINA_PARA at all. These parameters are mapped to the standard PROFIdrive Telegram 1, 2, 3, 4, 6, 7, 9, 102, 103, 105, 106 etc. The S7-1500 hardware identifier of the ZSW1 slot is wired into the HW_IDZSW input of the standard "SINAMICS" library block, and the entire word arrives in the cyclical I/O image. The bit to read is then accessed via:

#MotorOvertempAlarm_52_13 := "DB_Telegram".ZSW1.X13;

Use SINA_PARA only for:

• Drive parameters that are not mapped to the standard telegram (r21, r482, r977, p2155, custom user-defined words).
• Reading parameter sub-indices (e.g. r977[0..30] — the drive firmware version array).
• Writing parameters at commissioning (e.g. p1120, p1121 ramp times; p2155 thresholds).

Step-by-Step Commissioning Procedure for FB287

1. Open the TIA Portal project containing the S7-1500 station that is wired to the SINAMICS drive.
2. Install the matching "SINAMICS blocks" library from Siemens Industry Online Support. Restart TIA Portal so the master data is refreshed.
3. Insert a new global DB (e.g. DB_Commission) and create a static variable fbPara of type FB287 (single instance).
4. Add a tag StatusWord_52 of type WORD and a tag bBit13 of type BOOL.
5. From the project tree, drag the required hardware identifier (right-click the parameter channel slot under the drive's PROFINET interface, "Properties", "System constants") and wire it to HW_ID_Parameter of the FB287 instance.
6. Write the request: siParaNo := 52; siIndex := 0; syType := 0; ReadWrite := FALSE; Start := rising-edge trigger.
7. Add an OB1 / OB35 call of the FB287 instance with the wired inputs.
8. Compile and download to the S7-1500.
9. Force Start := TRUE once from the watch table. Confirm Busy = TRUE, then Done = TRUE with Error = FALSE.
10. Open the watch table, monitor StatusWord_52 as HEX, and confirm the upper 16 bits of the srValue cast match the expected r52 content from STARTER / Startdrive / the SINAMICS web server.
11. Apply the AND-mask 16#2000 and verify bBit13 toggles with the alarm state.

Verification Procedure

Troubleshooting Matrix

Performance and Cycle Time Considerations

Each SINA_PARA call opens a single PROFIdrive acyclic transaction. The request is queued behind the cyclical I/O data, so the typical round-trip time on PROFINET IRT is 30 to 60 ms, on PROFINET RT 40 to 80 ms, and on PROFIBUS DP-V1 20 to 50 ms. The acyclic channel is also serialized at the drive — calling the same drive object with FB286/FB287 from multiple OBs does not parallelize the traffic; only one request is processed at a time. The recommended practice is:

• Bundle all required parameter reads into a single FB286 call with NumberOfPara equal to the number of distinct parameters.
• Trigger the call from a time-controlled OB (OB30-OB38) rather than the OB1 freewheel to bound the load on the controller.
• Do not poll faster than 50 ms; faster cycles do not speed up the acyclic channel and consume both controller and drive CPU time.
• For bit-level alarms that need <10 ms reaction time, route the bit via p2099 / p2051 to the cyclical PZD rather than using SINA_PARA.

Field-Proven Patterns and Edge Cases

• Storing the 16-bit read in an INT and using x%DBxy.int_value X13 is not legal SCL: the AT-view or the shift-and-mask pattern is required.
• If the parameter is declared as 32-bit (DWORD) in the drive, the value lands in sdValue (DINT), and you can directly test sdValue.X13 after reading.
• For firmware-version reads (r977[0..30]), use siIndex = 0..30 and read each sub-index in a separate SINA_PARA request — there is no array read support in PROFIdrive.
• On a S7-1200, FB286 is limited to 4 parameters per call. If you need more, do two consecutive calls but respect the busy handshake between them.
• Make sure the DriveObjectNo input matches the topology: writing r52 to the wrong drive object is not an error (the write succeeds at the wrong place); reading r52 from the wrong object returns zeros with no error flag.

Alternative: Direct PROFINET Cyclic Bits

When only one or two bits are needed at high update rate, use SINAMICS free p2099 + p2051 routing. The procedure is documented in the SINAMICS S120 Function Manual. After configuration, the bit lands in the cyclical PZD and is accessible in the PLC without any acyclic call. This is the right answer for "Overtemperature alarm" bits that are part of a safety or fast-stop chain.