Industrial Automation
For the IMM procurement team evaluating the 2026 encoder RFQ, the Physis high-resolution servo motor line, the encoder resolution and positioning accuracy application note, and the VICKS contact page are the three reference resources, and the VICKS motion engineering team supports the encoder-battery qualification request for IMM machine commissioning review.
Why Absolute vs Incremental Is the Encoder Decision That Decides Whether Your Home Position Survives a Power Cycle
The absolute-vs-incremental encoder decision decides whether the home position on an IMM survives a power cycle, and it is the decision the machine builder locks at commissioning because the encoder type and the multi-turn retention architecture together determine the operator's recovery time the morning after a power-down event. The two architectures behave very differently under power-cycle conditions, and the difference is most visible on a Monday morning after a holiday-weekend power interruption.
An absolute encoder retains shaft position because the disc carries a unique binary code at every angular position and the electronics read the code on every power-up without rotating the motor. The electronics retain counts either in a battery-backed RAM cell or in a gear-driven mechanical counter. The home position survives a power cycle because the electronics remember where the shaft was when power dropped, and the IMM controller resumes production without homing.
An incremental encoder loses shaft position the moment power drops because the disc only carries a single pulse track and the electronics only count pulses while power is present. The IMM controller must rotate the motor to a known reference (limit-switch or datum marker) before production resumes. On a 5-axis IMM this takes 2 to 5 minutes per axis, and a full home sequence takes 30 to 90 minutes of operator-wait time.
The decision is therefore a question of operator-time cost per power-cycle event — 2 minutes or 90 minutes — not "better vs worse." The right answer depends on the IMM's production environment (continuous vs shift-based), operator-staffing profile, and the battery or service-life requirement on the absolute encoder architecture.
Encoder Resolution and Positioning Accuracy — The 17-bit to 23-bit Stack the IMM Cycle Reads
Encoder resolution and positioning accuracy is the headline technical stack the IMM machine builder reads on the encoder data sheet, resolving into two distinct numbers: encoder resolution (17-bit, 20-bit, or 23-bit) and positioning accuracy (the composite metric the buyer reads as per-axis positioning repeatability).
Encoder resolution defines the theoretical position granularity the servo loop reads. A 17-bit encoder delivers 131,072 unique positions per revolution; 20-bit delivers 1,048,576; 23-bit delivers 8,388,608. The theoretical angular resolution is 360° / 2^resolution. For a 23-bit encoder on a 10 mm pitch ball screw, the theoretical linear resolution is approximately 4.3 nanometers per encoder count.
Positioning accuracy is not the same number as encoder resolution. It decomposes into three contributors: mechanical transmission backlash (40-50% of total error), servo-loop gain error (30-40%), and encoder resolution limit (15-25%). A 23-bit encoder with excellent alignment delivers ±0.5 arcmin at the motor shaft, but the same encoder on a worn ball screw with 0.05 mm backlash delivers ±3 arcmin or worse at the load.
The ISO 230-2 test-code standard is the international reference the IMM builder reads against the positioning-accuracy decomposition, and IEC 61800-5-2 is the safety-functions reference for STO integration. For buyers, doubling the encoder resolution from 17-bit to 23-bit reduces the encoder-resolution-limit contribution from approximately ±5 arcmin to ±0.5 arcmin at the motor shaft, but does not change backlash or gain-error contributions. The upgrade is right when positioning error is dominated by encoder resolution (high-precision optical or medical parts), and wrong when dominated by mechanical backlash (older machines with worn ball screws).
Multi-Turn Battery Retention — The Battery Failure That Wipes Your Home Position Mid-Shift
The multi-turn battery retention architecture is the encoder-side detail the IMM operator notices first when it fails. The failure mode is rarely the encoder electronics failing — it is almost always the multi-turn counter battery reaching end-of-service-life mid-shift.
The battery-backed absolute encoder architecture uses a primary lithium cell (BR-series coin cell, CR-series coin cell, or TL-series lithium thionyl chloride cylindrical cell) to retain the multi-turn counter value when the encoder's main power drops. The encoder electronics check the battery voltage on every power-up and raise an alarm flag if the voltage drops below the manufacturer's threshold (typically 2.7-2.9 V for a 3 V lithium cell). Battery service life is 3 to 5 years at room temperature, halving for every 10°C above 25°C.
The mid-shift failure mode the operator notices is: the encoder raises the battery-low alarm, the IMM controller logs the alarm and continues running on the last-known-good multi-turn value, the counter eventually drops to zero as the voltage falls below the encoder's minimum operating voltage, and the IMM controller loses the home-position offset the next time the operator presses start-cycle after a power-down event. The operator arrives the next morning, presses start, and the IMM controller prompts for a full homing sequence.
The IEC 60529 IP-rating standard is the international reference the IMM builder reads against the encoder housing environmental rating. The gear-driven mechanical multi-turn architecture eliminates the battery failure mode entirely — the counter is retained by a mechanical gear train rather than a battery-backed RAM cell, rated for 10 to 20 years. The trade-off is bulk, and a small rotational drag the servo loop reads as a friction term. The gear-driven design is the right choice for buyers who prioritize long-term service life over initial cost; the battery-backed design is right for buyers who prioritize initial cost over the battery-replacement maintenance burden.
The Home-Position Recovery Sequence the IMM Controller Runs After a Power-Cycle Event
The home-position recovery sequence the IMM controller runs after a power-cycle event is the operator-wait sequence the IMM procurement team tries to minimize, and the sequence length depends on the encoder type the machine builder specifies and the homing procedure the machine builder programs into the IMM controller. Three architectures are common across the IMM market.
The first architecture is the absolute-encoder-with-battery architecture, and the recovery sequence is: the IMM controller reads the absolute position from the encoder on power-up, verifies the multi-turn counter value against the battery-backed RAM cell, and resumes production without a homing sequence if the multi-turn counter value is valid. The recovery sequence takes 2 to 10 seconds per axis (the time required for the encoder electronics to initialize and the IMM controller to read the absolute position), and the operator-time cost is minimal.
The second architecture is the absolute-encoder-with-battery-failure architecture, and the recovery sequence is: the IMM controller reads the absolute position from the encoder on power-up, detects that the multi-turn counter value is invalid because the battery has failed, and prompts the operator for a full homing sequence. The homing sequence takes 2 to 5 minutes per axis depending on the axis travel, the homing speed, and the deceleration profile the machine builder specifies.
The recovery sequence duration the IMM controller logs against the ISO 230-2 positioning repeatability test report is the operator-time cost the IMM service team tracks for the homing-sequence log. The third architecture is the incremental-encoder architecture, and the recovery sequence is the same as the absolute-encoder-with-battery-failure architecture on every power-down event because the incremental encoder never retains shaft position. The incremental encoder is the right choice for IMM buyers who want a lower-cost encoder stack and who are willing to absorb the homing-sequence operator-time cost on every power-down event.
For IMM buyers walking the encoder RFQ, the right architecture depends on the IMM's production environment. Continuous-production IMMs (24/7 medical-device molding, packaging-line IMMs) typically specify absolute encoders with battery-backed multi-turn retention because the operator-time cost of a homing sequence on a continuous-production line is significant. Shift-based-production IMMs (job-shop molding, custom-part molding) often specify incremental encoders because the homing sequence at the start of every shift is a small operator-time cost relative to the per-shift setup time the IMM already absorbs.
The Battery Qualification Procedure the IMM Commissioning Engineer Runs at First Power-Up
The battery qualification procedure the IMM commissioning engineer runs at first power-up is the procedure the IMM service team uses to set the battery-replacement schedule, and the procedure resolves into four measurements the commissioning engineer runs against the encoder manufacturer's published specifications.
The first measurement is the open-circuit voltage check: the commissioning engineer measures the battery voltage at the encoder-side battery terminals with the encoder disconnected from the encoder electronics, and verifies the open-circuit voltage is within the manufacturer's specified range (typically 2.9 to 3.2 V for a fresh primary lithium cell). The open-circuit voltage check is a quick sanity check that catches a battery that has been on the shelf past its shelf-life date.
The second measurement is the load-test voltage check: the commissioning engineer measures the battery voltage while the battery is connected to the encoder electronics and the encoder electronics are drawing the standby current the manufacturer specifies (typically 1 to 10 µA for a battery-backed absolute encoder). The load-test voltage check is the measurement that catches a battery whose internal resistance has increased with age, and the load-test voltage should remain above the encoder's minimum operating voltage (typically 2.7 V) under the specified standby current.
The third measurement is the expected-service-life calculation: the commissioning engineer calculates the expected service life from the battery manufacturer's published self-discharge rate and the encoder's published standby current, and verifies the calculated service life is consistent with the IMM's preventive-maintenance schedule. The expected-service-life calculation catches a battery whose chemistry is mismatched to the encoder's standby current profile.
The ANSI/UL 61800-5-1 safety standard for adjustable-speed electrical power drive systems is the North American reference the IMM builder reads against the encoder-side in-cabinet thermal envelope. The fourth measurement is the environmental-derating calculation: the commissioning engineer applies the manufacturer's published temperature-derating curve to the expected service life, and verifies the derated service life is consistent with the IMM's preventive-maintenance schedule under realistic in-cabinet thermal conditions. The environmental-derating calculation is the measurement that catches a battery whose chemistry is rated for room temperature only but is being deployed in an in-cabinet environment that runs 10 to 15°C above room temperature.
The 7-Item Encoder-Side RFQ Checklist an IMM Procurement Team Can Hand to a Servo Motor Supplier
The 7-item encoder-side RFQ checklist an IMM procurement team can hand to a Servo Motor supplier is the checklist the machine builder uses to lock the encoder specification at machine commissioning. The checklist walks the buyer through seven encoder-side items the machine builder reads on the encoder data sheet and the supplier responds to with a written line-item answer.
1. **Encoder type and resolution** — absolute vs incremental, single-turn vs multi-turn, bits (17/20/23-bit), interface protocol (SSI, BiSS, EnDat, Hiperface, Nikon, Tamagawa). The supplier responds with the encoder model number and the interface protocol the IMM controller reads at the servo-drive interface.
2. **Multi-turn retention architecture** — battery-backed counter, gear-driven mechanical counter, or single-turn only. Supplier responds with the retention architecture and counter range (16-24-bit battery-backed, 12-16-bit gear-driven).
3. **Battery specification** — chemistry (BR-series carbon monofluoride, CR-series manganese dioxide, TL-series thionyl chloride), nominal voltage, expected service life at 25°C and 45°C in-cabinet, and the replacement procedure the IMM service team runs. Supplier responds with the battery datasheet and the service-life calculation.
4. **Encoder cable specification** — length, jacket material (PVC/PUR/TPE), shielding (foil/braid/double), minimum bend radius, encoder-side connector. Determines the encoder's environmental durability and noise immunity from the Servo Drive and plasticizing motor.
5. **Environmental rating** — IP rating at the housing (IP65 standard industrial, IP67 harsh), operating and storage temperature range, vibration and shock rating. Determines whether the encoder survives the IMM's in-cabinet thermal and vibration environment.
6. **Safety-function integration** — STO (Safe Torque Off), SS1 (Safe Stop 1), SLS (Safely Limited Speed) integration, plus the safety-function test-report documentation for CE compliance per IEC 61800-5-2, the North American ANSI/UL 61800-5-1 standard, and the UL functional-safety certification program that the IMM machine builder references for end-customer CE/UL compliance.
7. **Commissioning-time encoder-battery qualification procedure** — the procedure the IMM commissioning engineer runs at first power-up, the procedure the IMM service team runs at every preventive-maintenance interval, and the documented battery-replacement schedule. Converts the encoder specification into the IMM's preventive-maintenance schedule.
For buyers walking this RFQ checklist with a Physis high-resolution servo motorsupplier, the checklist produces a written line-item answer that the IMM procurement team reads against the encoder data sheet the machine builder specifies, and the line-item answer becomes the encoder-side RFQ response the IMM procurement team compares across multiple Servo Motor suppliers.
When the Encoder Battery Failure Surfaces Mid-Shift — The Operator-Side Failure Mode
The encoder battery failure mid-shift is the operator-side failure mode the IMM service team plans for, surfacing in three predictable patterns across the IMM fleet: gradual-decay, sudden-failure, and temperature-induced-failure.
The gradual-decay pattern produces predictable warning signs. The encoder raises the battery-low alarm weeks or months before the counter drops to zero, and the service team sees the alarm on the controller's diagnostic screen and schedules a replacement before failure. The preventive-maintenance schedule is designed to catch this pattern, and an IMM that runs preventive maintenance on time never sees a mid-shift event.
The sudden-failure pattern produces no warning signs. The encoder loses the multi-turn value between two consecutive power-up events with no alarm flag in between, and the operator sees the homing-sequence prompt the next morning. The service team responds by replacing the battery and running the homing sequence on every axis in error.
The temperature-induced-failure pattern appears in in-cabinet environments running hotter than room temperature, producing a shorter-than-expected service life because self-discharge doubles for every 10°C above 25°C. The environmental-derating calculation at first power-up catches this, and the commissioning engineer adjusts the replacement schedule accordingly.
For buyers walking the encoder RFQ, the right preventive-maintenance schedule depends on the architecture. The battery-backed architecture requires replacement at the manufacturer's published interval (3-5 years at 25°C, 1.5-2.5 years at 45°C in-cabinet). The gear-driven-mechanical-counter architecture requires no battery schedule but a periodic mechanical inspection every 5 to 10 years to verify gear-train backlash. The incremental-encoder architecture requires neither.
The Encoder Specification vs the IMM Cycle-Time Specification — Where the Two Decouple
The encoder specification and the IMM cycle-time specification are the two specifications the IMM machine builder reads together, and the two decouple in three predictable patterns across the IMM market: the encoder-over-specified pattern, the encoder-under-specified pattern, and the encoder-mismatched pattern.
The encoder-over-specified pattern is the encoder-specification pattern the IMM machine builder sees when the encoder resolution exceeds what the IMM's positioning-accuracy budget requires. A 23-bit encoder on an IMM that runs a packaging-line mold with a 0.5 mm wall-thickness tolerance is over-specified because the encoder-resolution-limit contribution (approximately ±0.5 arcmin at the motor shaft) is well below the wall-thickness tolerance the mold designer specifies. The 23-bit encoder on a packaging-line IMM is a quality-of-specification choice rather than a cycle-time requirement, and the IMM procurement team can downgrade to a 20-bit encoder and save the encoder-cost premium without affecting the IMM's cycle-time specification.
The encoder-under-specified pattern is the encoder-specification pattern the IMM machine builder sees when the encoder resolution falls below what the IMN's positioning-accuracy budget requires. A 17-bit encoder on an IMM that runs an optical-part mold with a 0.05 mm wall-thickness tolerance is under-specified because the encoder-resolution-limit contribution (approximately ±5 arcmin at the motor shaft) is well above the wall-thickness tolerance the mold designer specifies. The 17-bit encoder on an optical-part IMM is a cycle-time bottleneck, and the IMM procurement team upgrades to a 23-bit encoder to bring the encoder-resolution-limit contribution below the wall-thickness tolerance the mold designer specifies.
The Oriental Motor servo-encoder technical terminology guide and the Yaskawa servo motor encoder application guideare the two technical references the IMM machine builder reads against the encoder interface protocol selection. The encoder-mismatched pattern is the encoder-specification pattern the IMM machine builder sees when the encoder interface protocol the encoder supports is not the encoder interface protocol the IMM's Servo Drive supports. An EnDat encoder on an IMM whose Servo Drive supports BiSS is encoder-mismatched because the encoder interface protocol the encoder electronics speak is not the encoder interface protocol the Servo Drive listens to. The encoder-mismatched pattern is the encoder-side detail the IMM procurement team catches at the encoder-side RFQ checklist, and the IMM procurement team locks the encoder interface protocol at the encoder-side RFQ rather than at the encoder-side commissioning.
For IMM buyers walking the encoder RFQ, the right encoder specification is the one that matches the IMM's positioning-accuracy budget without inflating it beyond what the cycle-time specification requires. The 23-bit encoder is the right choice for the high-precision IMM, and the 17-bit encoder is the right choice for the packaging-line IMM, and the encoder-side decision the IMM procurement team locks at commissioning is the decision the IMM operator lives with for the encoder's full service life.
The VICKS Servo Encoder Stack — How the Physis Line Handles the Absolute vs Incremental Decision
The VICKS Servo encoder stack is the encoder stack the Physis high-resolution servo motor line supports, and the encoder stack resolves into three options the IMM machine builder reads on the encoder data sheet: the 23-bit absolute encoder with battery-backed multi-turn retention, the 23-bit absolute encoder with gear-driven mechanical multi-turn retention, and the 17-bit incremental encoder.
The Heidenhain high-resolution optical encoder knowledge base is the technical reference the IMM machine builder reads against the absolute-encoder optical-disk design choices. The 23-bit absolute encoder with battery-backed multi-turn retention is the encoder option the IMM machine builder specifies for the continuous-production IMM that requires zero-hom-sequence recovery on every power-down event. The battery-backed architecture retains the multi-turn counter value through power-down events, and the IMM controller resumes production without a homing sequence. The expected service life at 25°C is 5 years, and the expected service life at 45°C in-cabinet is 2 years, and the preventive-maintenance schedule is a 2-year battery-replacement interval.
The 23-bit absolute encoder with gear-driven mechanical multi-turn retention is the encoder option the IMM machine builder specifies for the continuous-production IMM that requires zero-hom-sequence recovery and a longer preventive-maintenance interval. The gear-driven architecture eliminates the battery failure mode entirely, and the IMM service team runs a periodic mechanical-inspection schedule at 10-year intervals to verify the gear-train backlash is within the manufacturer's published specification. The gear-driven architecture is the right choice for the IMM that prioritizes long-term service life over initial cost.
The 17-bit incremental encoder is the encoder option the IMM machine builder specifies for the shift-based-production IMM that absorbs the homing-sequence operator-time cost at the start of every shift. The 17-bit incremental encoder is the lowest-cost encoder option the Physis high-resolution servo motor line supports, and the incremental encoder is the right choice for the IMM whose positioning-accuracy budget is dominated by mechanical backlash rather than encoder resolution.
For IMM buyers walking the encoder RFQ with the VICKS engineering team, the encoder-side RFQ response the buyer reads against the encoder-side RFQ checklist produces a written line-item answer the IMM procurement team compares across multiple encoder architectures, and the line-item answer becomes the encoder specification the IMM machine builder locks at commissioning.
How Buyers Translate the Encoder Specification into a Motor Specification That Actually Fits
The encoder specification the IMM machine builder locks at commissioning is the one the buyer translates into a motor specification that fits. The translation requires four machine-side inputs the buyer reads against the encoder data sheet: positioning-accuracy budget, cycle-time specification, preventive-maintenance window, and commissioning protocol.
The positioning-accuracy budget is read against the encoder resolution — the right resolution matches the budget without exceeding it. 23-bit for high-precision IMM, 20-bit for standard-precision, 17-bit for packaging-line.
The cycle-time specification is read against the encoder's maximum data-transmission rate — the right interface protocol supports the cycle-time data rate at the encoder's max motor speed. A 23-bit encoder at 6,000 RPM generates a data rate the protocol must support; SSI tops out lower than BiSS or EnDat.
The preventive-maintenance window is read against the encoder's PM schedule — the right architecture fits inside the IMM's PM window. Battery-backed: 2-year replacement; gear-driven: 10-year mechanical inspection; incremental: no schedule.
The commissioning protocol is read against the encoder's commissioning procedure — the right architecture's procedure the engineer can run at first power-up without specialized tools. Battery-backed: voltage check, load-test, service-life calculation, environmental-derating. Gear-driven: mechanical-backlash verification. Incremental: homing-sequence verification.
For buyers walking the encoder-to-motor translation, the encoder resolution and positioning accuracy application note walks the per-cycle positioning accuracy decomposition the IMM builder reads against the cycle-time spec, and the Physis high-resolution servo motor data sheet walks the per-architecture option the buyer reads against the PM window.
Frequently Asked Questions
Q1:What is the typical service life of the multi-turn backup battery in an IMM absolute encoder, and what is the right replacement interval the IMM service team should plan for??
A primary lithium cell (BR-series or TL-series) typically lasts 5 years at room temperature, halving to 2 years at 45°C in-cabinet (self-discharge doubles per 10°C above 25°C). The right replacement interval for a continuous-production IMM at 45°C is 18 to 24 months (6 to 12 month safety margin); for shift-based IMMs at 25°C, 4 to 5 years. The service team should log the replacement date on the encoder label and in the PM record, and run a battery-voltage check at every preventive-maintenance visit to catch a battery degrading faster than the calculated rate.
Q2:Can an IMM machine builder upgrade an incremental encoder to an absolute encoder mid-life, and what does the upgrade involve at the hardware and software level??
Yes, but the upgrade is rarely drop-in — the interface protocol, servo-drive firmware, and IMM controller software all change with the architecture. Hardware: replace the encoder with the same form-factor absolute (where available) and verify the cable is rated for the new data rate. Software: update the servo-drive firmware for the new protocol (EnDat, BiSS, Hiperface), update the IMM controller to read absolute on power-up, and update homing logic to skip when absolute is valid. Typically 2 to 5 working days for a qualified service team.
Q3:How does the gear-driven mechanical multi-turn counter architecture compare to the battery-backed architecture on long-term reliability and preventive-maintenance burden??
The gear-driven mechanical multi-turn counter eliminates the battery failure mode entirely — no battery, and the gear train is rated for the encoder's full 10 to 20 year service life. Trade-offs: bulk, cost, and a small rotational drag the servo loop reads as a friction term. PM burden is a mechanical inspection every 5 to 10 years rather than a battery replacement. For long-term-reliability buyers, gear-driven is right despite higher initial cost. For initial-cost buyers, battery-backed is right with the replacement burden on the IMM service team's PM schedule.
Q4:What is the positioning-accuracy decomposition the IMM machine builder reads on the test report, and how does the decomposition change when the encoder resolution is upgraded from 17-bit to 23-bit??
Positioning accuracy decomposes into three contributors: mechanical transmission backlash (40-50% of total error), servo-loop gain error (30-40%), and encoder resolution limit (15-25%). Upgrading from 17-bit to 23-bit reduces the encoder-resolution contribution from approximately ±5 arcmin to ±0.5 arcmin at the motor shaft, but does not change backlash or gain-error contributions. The upgrade is right when error is dominated by encoder resolution (high-precision optical or medical parts), wrong when dominated by mechanical backlash (older machines with worn ball screws).
Q5:Is the encoder-side RFQ the right place to lock the encoder interface protocol, or should the IMM procurement team lock the protocol at the servo-drive RFQ??
The encoder-side RFQ is the right place to lock the encoder interface protocol because the protocol is determined by the encoder model number, which is locked at the encoder-side RFQ. The servo-drive RFQ should specify which encoder interface protocols the drive must support (EnDat, BiSS, Hiperface, SSI), and should require support for at least two of these protocols to give the encoder-side RFQ flexibility to select the optimal encoder for the IMM's positioning-accuracy budget. Buyers who lock the encoder interface protocol at the encoder-side RFQ rather than the servo-drive RFQ end up with a more flexible encoder-side RFQ response and a more defensible encoder specification.
Q6:What is the typical lead time for a custom absolute encoder with non-standard battery specification or non-standard multi-turn counter range??
The typical lead time for a custom absolute encoder with non-standard battery specification is 8 to 12 weeks for a sample and 12 to 16 weeks for production. Lead time depends on the manufacturer's battery qualification cycle (4 to 6 weeks for a new chemistry or manufacturer) and the multi-turn counter qualification cycle (6 to 8 weeks for a new range). Buyers walking a custom-encoder RFQ should plan for a 4-month total horizon including sample evaluation, production qualification, and PM schedule verification.
Q7:What is the operator-time cost of a full homing sequence on a 5-axis IMM with incremental encoders, and how does the operator-time cost compare to the per-cycle commissioning cost of an absolute-encoder architecture??
The operator-time cost of a full homing sequence on a 5-axis IMM with incremental encoders is 30 to 90 minutes depending on axis travel, homing speed, and deceleration profile. The per-cycle commissioning cost of an absolute-encoder architecture is 2 to 10 seconds per axis. Cumulative operator-time cost on a continuous-production IMM with one power-down per month is 6 to 18 hours/year; with one power-down per week, 26 to 78 hours/year. This differential is the input the procurement team uses to decide whether the absolute encoder's higher initial cost is justified by the operator-time reduction.
Q8:How does the encoder-battery qualification procedure change when the IMM is deployed in a high-vibration or high-shock environment??
For a high-vibration or high-shock IMM, the qualification procedure is the same but the expected-service-life calculation adds vibration-derating (10-30% reduction depending on the encoder's vibration rating) and shock-derating (20-50% depending on shock rating). Replacement interval for a high-vibration IMM is 12 to 18 months (vs. 18 to 24 standard), and 6 to 12 months for high-shock. The commissioning engineer should verify the vibration and shock ratings against the deployment environment at first power-up and adjust the preventive-maintenance schedule accordingly.