Troubleshooting Sinumerik 802D Alarm 700016 Drive Not Ready

Alarm 700016 Definition and Operational Context

Alarm 700016 on a Siemens SINUMERIK 802D numeric control paired with a SIMODRIVE 611 power section is a system-level alarm that signals the drive system is not ready to accept motion commands. The alarm is raised at the HMI immediately on power-up or reset, persists after the operator presses the physical ENB (enable) button, and reappears together with follow-on faults such as alarm 300 (emergency stop). The 802D PLC user program is the source of the message: the alarm number is not a standard Siemens NCK code from the kernel itself, but a custom bit raised inside the machine builder's PLC logic and exposed to the HMI through the alarm handler. That means the exact text mapped to 700016 varies between machine builders, but the canonical meaning is drive not ready.

Per the SINUMERIK 808D ADVANCED Service Manual (ID: 109763684), the formal description of alarm 700016 in the 808D documentation lineage is:

The drive is not ready for operation. Note: this alarm always appears along with the alarm of emergency stop.

Although the 802D and 808D are different control generations, the alarm numbering, the underlying Profibus-to-Simodrive-611 handshake, and the required enable-chain conditions are functionally equivalent. The 808D Service Manual (ID: 109745111) additionally documents that this alarm category is also raised when the lubricating oil level in the oil box drops below the minimum set value, in which case mechanical damage can result if no remedy is applied. Field practice shows that 700016 is therefore a family of drive-not-ready conditions, and the user must trace the PLC logic to identify which underlying condition is true.

Companion Alarm 300 and the Emergency-Stop Relationship

Alarm 300 is the 802D's emergency-stop (E-stop) channel alarm. It is raised when any safety-relevant contact chain in the E-stop loop, the limit-switch chain, or the drive controller-inhibit chain is open. The official Siemens documentation states that alarm 700016 always appears together with an emergency-stop alarm. In practice, the PLC user program raises 700016 as a derived consequence of the 300 condition; clearing 300 is therefore a prerequisite to clearing 700016.

When the operator presses the ENB button on the operator panel, the HMI sends a request back to the PLC, which is supposed to drop the inhibit on the drive group. If the drive is still not ready, the PLC re-asserts the inhibit and 700016 returns. The ENB button itself does not directly drive the power module — it sets a bit in the PLC, and the PLC program must propagate the request through several safety and enable interlocks before the drive is actually enabled.

System Architecture: 802D, Simodrive 611, and Profibus

The classic 802D + SIMODRIVE 611 topology uses a Profibus-DP link between the 802D (master) and one or more 611 power modules (slaves). The 611 power module is a modular unit consisting of:

• NE (Netz-Einspeisung) — the line-side infeed module that rectifies the 3-phase supply into the DC link.
• E/R (Enable / Regulate) — the controller-enable and pulse-enable logic, often implemented as terminals 63, 64, 48, and the 663/65 enable pair.
• Power Module (1-axis or 2-axis) — the IGBT output stage that drives the 1FK/1FT servomotor.

The 802D communicates with the 611 over Profibus-DP using the standard Siemens drive telegram (typically Standard Telegram 3 or Standard Telegram 5). Through this bus, the NCK sends position setpoints, and the drive returns actual position, torque, and status bits. The drive's ready-to-operate state is communicated in the status word (ZSW1 bit 0, or for Simodrive 611 the equivalent RDO bit). Critically, the Profibus status word is only valid if the hardware enables are present at the drive terminals. A missing terminal enable will cause the drive to be offline on the bus even if Profibus communication itself is healthy.

Enable Signal Paths: Terminals 63, 64, and 48

The 611 drive module requires three hardware enables before it can accept motion commands. These are wired to specific terminals on the NE module and on the controller module:

For the 802D platform, the standard wiring practice is for the PLC user program to drive terminals 63 and 64 (sometimes 48 as well) through 24 V outputs. When the operator presses the ENB button, the PLC debounces the input, verifies all safety conditions, and energizes these outputs. If any of these terminals is missing 24 V, the drive's internal logic will not leave the not-ready state, the Profibus status word will reflect not ready, and the PLC will re-assert 700016.

Profibus-Connected vs Hardwired Drive Enable

The 802D supports two philosophies for issuing the controller-enable to the 611 drive:

1. Hardwired enable — The PLC drives 24 V onto terminals 63, 64, 48 directly. The Profibus status word is read by the PLC to verify the drive's response, but the enable itself does not traverse Profibus.
2. Profibus-only enable — The PLC sends a control-word bit (typically STW1 bit 0 = ON/OFF1, STW1 bit 1 = OFF2, STW1 bit 2 = OFF3) over the Profibus telegram. The drive's internal logic then energizes the IGBTs without an external terminal signal.

Many retrofitters mix the two: the safety chain (OFF2, OFF3) is hardwired, and the operational enable (ON/OFF1) is sent over Profibus. The source case is exactly this mixed topology — the ENB button is mapped through the PLC, the PLC sends the relevant Profibus control-word bit, but the hardware enables at 63/64/48 are still required. A missing terminal enable will keep the drive offline even when the Profibus control word is correct.

How to determine which path is in use

1. Open the 802D commissioning manual for the machine or, in its absence, the Siemens Product Support page for SINUMERIK 802D.
2. Search the machine builder's wiring diagram for the 611 module. If 24 V appears at terminals 63/64/48 from a PLC output, the path is hardwired. If those terminals are jumpered to 24 V at the drive end, the path is Profibus-only.
3. Cross-check by reading the PLC project — the FBD/LAD source should show a coil driving an output that energizes the 611 enable terminal (or, alternatively, a function block that writes a Profibus control-word bit to the drive).

PLC Program Cross-Reference for the ENB Button

The ENB button is wired into a digital input on the 802D PLC. The mapping from input terminal to internal flag is defined in the PLC configuration. To find the bit that the ENB button sets, follow this cross-reference procedure in PLC Programming Tool (Programming Tool PLC802 or the matching Step 7 / Step 7 Micro / WinSPS-S7 variant shipped with the 802D):

1. Open the PLC project corresponding to the 802D firmware installed on the controller. The PLC project file is normally stored on the MMC card and can be loaded via the Programming Tool.
2. Open the Symbol Table and search for symbols containing ENB, ENABLE, EIN, DRV_EN, or localized variants such as FREIGABE.
3. For each candidate symbol, right-click and select Cross Reference (Querverweis). This produces a list of every network that reads or writes the flag.
4. Trace the input assignment first: locate the OB1 segment (or input image segment) that maps the physical input to the flag. Note the I address (e.g. I 0.5).
5. Trace the consumers: every network that uses the flag is part of the enable chain. The final network in the chain is normally a coil that drives the hardware enable output (e.g. Q 0.4 for terminal 63) or that calls a function block writing the Profibus control word.
6. Walk the chain from button to coil. Any network that contains an AN (AND-NOT) on a safety input (E-stop, axis-limit, door-switch, hydraulic-pressure OK) is a candidate to keep the drive inhibited.

The address of the ENB button itself is machine-specific and not standardized across 802D installations. Without the machine builder's PLC source, the address cannot be derived from Siemens documentation alone.

Drive Status Indicators and Diagnostic Reading

On the 802D HMI, navigate to Diagnostics > Drive Service (or the equivalent menu in the 802D base software) to read the live status of the Simodrive 611 axes. Useful signals to record:

Although the source case reports that the drive shows RUN on the 611 status LEDs, this is consistent with the 611 having the line contactor pulled in and the IGBTs not faulted. The RUN LED alone does not confirm that the controller enable has been accepted — only the controller module's internal handshake does. Cross-check the diagnostic screen on the 802D, not the LED on the drive.

Safety Circuit and E/R Module Verification

Before assuming a PLC logic problem, the safety chain must be physically verified. On most 802D + 611 retrofits the safety chain runs through the following sequence, all of which must be closed before the drive can be enabled:

1. E-stop button (NC contact) — series-wired in the safety loop. Multimeter-check continuity with the button released.
2. Axis hardware limit switches (NC) — series-wired. An actuated limit switch opens the chain.
3. Door / guard interlock — typically a safety relay output. Verify the relay is in the energized state.
4. Safe standstill input (if equipped) — terminals 663/65 on the 611. Both must be at 24 V; 0 V on either issues OFF2 or OFF3 respectively.
5. Hydraulic / pneumatic pressure OK — many machines gate the controller enable on an auxiliary pressure switch.
6. DC link charged — the NE module signals NE ready to the PLC; if the pre-charge contactor is still open or has welded, the drive stays in not-ready.

A single open contact anywhere in this chain will hold the drive in the not-ready state. The PLC is the easiest place to read the chain state, because every safety contact is normally mapped to a digital input, and the PLC ladder shows the AND-tree that combines them.

Step-by-Step Troubleshooting Procedure

1. Power-cycle the 802D and the 611 NE module. Wait 30 seconds for the DC link to discharge and for the 611 to complete its self-test. Confirm the 802D boots without alarm 700016 in the alarm history; if it appears immediately on cold start, the fault is hard.
2. Read the alarm history on the 802D HMI (Menu > Diagnostics > Alarm Log). The 700016 entry will have a timestamp. Look for the immediately preceding alarm — usually 300 (emergency stop) or 3000 (axis enable missing). The preceding alarm tells you which chain has failed.
3. Open the 802D PLC project in the Programming Tool. Locate the network that raises alarm 700016 (search for the HMI alarm function block call). Trace the input condition that drives the alarm bit.
4. Cross-reference the drive-ready bit in the PLC. This is normally a flag such as M 100.0 or a data-word bit that reflects the Profibus status word bit 0. The alarm will be raised while this bit is 0.
5. Force the drive-ready bit OFF in the PLC monitor (online > force table) and observe whether the drive responds. This separates Profibus communication from hardware enable. If forcing the bit does not clear 700016, the alarm logic itself has a second source.
6. Walk the enable chain in the PLC from the ENB input to the terminal-63/64/48 outputs. Use the status display to confirm each rung transitions. Any rung whose output remains 0 in spite of all inputs being 1 is the failing network.
7. Check 24 V on the enable terminals with a multimeter. Terminal 48 should be 24 V referenced to terminal 9 (common) before the drive will respond. Terminals 63 and 64 should see 24 V only after the PLC has processed the ENB request.
8. Verify Profibus telegram by reading the control word and status word with the Programming Tool's diagnostic view or the 802D's drive service screen. If STW1 bit 0 is set but the drive is still not ready, the controller-enable handshake is failing inside the 611.
9. Inspect the E/R module LED pattern on the 611 controller card. The 611 displays fault codes via a 7-segment LED; refer to the SIMODRIVE 611 troubleshooting manual on Siemens Product Support for the LED-to-fault mapping.
10. Confirm axis enable bits DB380x.DBX2.1 (pulse enable) and the corresponding PLC flag. If the PLC is not setting the pulse-enable, the drive cannot leave the not-ready state regardless of the terminal voltages.

Verification and Commissioning Checks

After the fault has been located and corrected, perform the following verification before returning the machine to production:

1. Power on with all guards closed and the E-stop released. The 802D should boot to the operator screen with no active alarm 700016.
2. Press the ENB button. The alarm 300 (if any) should clear first, followed by the 700016 alarm clearing within 2 seconds.
3. Read the 802D drive service screen. Confirm the status word shows bit 0 = 1 and bit 1 = 1, and that the axis state is Position-controlled.
4. Jog each axis in JOG mode at low feed-rate (e.g. 500 mm/min). Confirm smooth motion with no fault.
5. Trigger the E-stop and confirm alarm 300 reappears, followed by 700016, and that the drive contactor drops within 250 ms.
6. Reset the E-stop and confirm that the alarms clear in the same order (300 first, then 700016) after pressing ENB.

Edge Cases and Related Alarm Conditions

Beyond the classic 700016 drive-not-ready scenario, the following adjacent conditions can produce a 700016 family alarm in the 802D + 611 architecture and should be checked when the standard enable chain appears intact:

Field-Proven Caveats

• The PLC program is the single source of truth for the 700016 alarm text and the conditions that raise it. Generic Siemens documentation can describe the alarm family, but only the machine builder can describe the exact boolean logic.
• The 611 RUN LED on the front of the drive is a coarse indicator — it reflects the line contactor state, not the controller-enable state. Always cross-check with the 802D drive service screen.
• Hardwired enables at terminals 63/64/48 and Profibus control-word bits are not redundant — both are required on most 802D + 611 retrofits. A correct Profibus STW1 alone is not sufficient.
• When the safety chain is open, the PLC should latch the drive-ready bit at 0; do not attempt to force the bit to 1 as a workaround, as this bypasses the safety chain.