Configuring Pre-Start Warning Alarms on SIMOCODE pro V with APL MotL and FbSwtMMS in SIMATIC PCS 7

To generate an audible horn or visual beacon warning alarm prior to starting a motor controlled by SIMOCODE pro V in SIMATIC PCS 7, use the APL motor block MotL (FB1823) coupled with the SIMOCODE driver block FbSwtMMS (FB1888). In MotL, configure the pre-start warning time parameters WarnTiMan (for operator manual starts) and WarnTiAut (for automated sequence starts) to the desired warning duration (e.g., 10.0 seconds). When a start command is issued, MotL asserts output WarnAct = 1 during the countdown to drive the pre-start warning horn, and only energizes the motor command output to FbSwtMMS once the timer expires.

Safety Requirements for Pre-Start Warning Alarms on Industrial Drives

In industrial manufacturing plants operating crushers, long overland belt conveyors, agitators, and slurry pumps, starting a high-power motor without prior notice poses severe personnel safety hazards. Personnel working near moving mechanical parts must receive an unambiguous acoustic warning (horn/siren) and visual warning (strobe beacon) before equipment rotates.

International safety standards (such as ISO 13849, OSHA, and EN 62061) mandate that a pre-start warning sound for a parameterized duration (typically 5 to 15 seconds) prior to contactor pull-in.

Architecture: APL MotL Control and FbSwtMMS SIMOCODE Driver

In SIMATIC PCS 7, intelligent low-voltage motor starters such as the SIMOCODE pro V (3UF7...) interface with the DCS via PROFIBUS DP or PROFINET using standard APL templates (SIOS Entry ID: 64182525):

MotL (Motor Large, FB1823): Executes the high-level operational control, operating mode management (Auto, Manual, Local), interlocking (Permit, Intlock, Protect), faceplate monitoring, and pre-start warning timers.
FbSwtMMS (Switchgear Motor Management Station, FB1888): Operates as the hardware driver block. It translates MotL commands into cyclic PROFIBUS/PROFINET control words (PZD) sent to SIMOCODE, while unpacking motor current, thermal overload, and operating state feedback.

Configuring Pre-Start Warning Times: WarnTiMan and WarnTiAut

The pre-start warning function in MotL is configured via two dedicated input parameters:

WarnTiMan (Warning Time Manual): Duration in seconds for the warning horn when the operator clicks 'Start' on the WinCC APL faceplate. Setting this value greater than 0.0 (e.g., 10.0 seconds) activates the function.
WarnTiAut (Warning Time Automatic): Duration in seconds for the warning horn when an automated SFC phase or plant start sequence commands MotL.AutModLi and MotL.StartAut.

When a start command arrives, MotL suppresses immediate contactor activation, sets output WarnAct = 1, and begins the internal countdown. The operator faceplate displays a distinctive warning notice indicating that the pre-start sequence is active.

Interconnecting the WarnAct Output to Horns, Beacons, and Alarms

To actuate field sirens and generate WinCC alarms:

Field Horn / Strobe Output: Connect MotL.WarnAct to a digital output channel block (Pcs7DiOu / CH_DO) wired to the physical horn relay or 24 VDC beacon.
SIMOCODE Internal Warning Output: If the warning horn is wired directly to an auxiliary output on the SIMOCODE pro V unit, map WarnAct through FbSwtMMS into an unassigned cyclic control bit in the SIMOCODE telegram, parameterizing the SIMOCODE internal logic to drive output relay Out 2 or Out 3.
Alarm Generation: MotL automatically records an operational message in WinCC Alarm Logging stating that the pre-start warning has commenced.

Pre-Start Warning Parameter and Timing Matrix

The following table summarizes MotL pre-start warning parameters and their behavior:

Parameter NameData TypeDefault ValueDescriptionTypical Industrial SettingWarnTiManREAL0.0 sPre-start warning duration for manual operator starts10.0 sWarnTiAutREAL0.0 sPre-start warning duration for automatic sequence starts10.0 sWarnActSTRUCT (Bool+ST)0Active warning signal; drives field horn/strobeConnect to CH_DO horn relayStartManBOOL0Operator faceplate start command pulseTriggered from WinCCFbkRunOutSTRUCT (Bool+ST)0Final motor running command sent to FbSwtMMSEnergizes after WarnTi expires

Verification

Verify the pre-start warning sequence through the following test steps:

Open the CFC chart online and monitor MotL and FbSwtMMS.
In WinCC Runtime, open the motor faceplate. Set operating mode to Manual.
Click Start. Verify that MotL.WarnAct immediately transitions to 1.
Confirm that the physical field horn sounds and the faceplate displays 'Pre-start warning active'.
Verify that MotL.FbkRunOut remains 0 and the motor contactor does not energize during the 10-second countdown.
After 10.0 seconds, verify that WarnAct transitions to 0, the horn silences, and FbkRunOut transitions to 1, starting the SIMOCODE motor cleanly.

Limitations and Operational Precautions

Consider these operational rules when configuring pre-start warnings:

Never Bypass Warning for Automatic Restarts: If a conveyor stops due to a temporary operational interlock and restarts automatically when the interlock clears, ensure WarnTiAut sounds before restarting.
Rapid Abort Handling: If the operator clicks Stop or an emergency interlock trips while WarnAct is counting down, MotL immediately aborts the timer, silences the horn, and cancels the start sequence.
Local LCS Starts: If the motor is started locally at the field pushbuttons, ensure the field panel includes a mechanical warning circuit or wire the local start contact into MotL.LocalLi so the DCS can sound the horn.

Engineer FAQ

Can I sound a horn for both manual and automatic starts?

Yes, configure both WarnTiMan and WarnTiAut. They can be set to the same duration or different durations according to plant safety requirements.

How does FbSwtMMS interface with SIMOCODE pro V?

FbSwtMMS exchanges standard cyclic DP/PN telegrams (such as Basic Type 1 or 2), transmitting run/stop control bits and receiving motor current, thermal memory, and fault codes.