PowerFlex 755 to 755TS Migration: What Stays, What Changes and a Plant Checklist

Rockwell publishes a dedicated guide for replacing a PowerFlex 755 with a PowerFlex 755TS: 750-RM102A-EN-P, PowerFlex 755 Drive to PowerFlex 755TS Drive Migration Guide (April 2024). This article summarises what that guide says — what stays the same and what changes — and turns it into a checklist for a drive replacement in a plant. Page numbers in brackets refer to 750-RM102.

What 750-RM102 covers

• Existing drive: PowerFlex 755, catalog 20G. New drive: PowerFlex 755TS, catalog 20G2 (standard protection) or 20GE (XT corrosive gas protection) (cover, p. 15).
• The guide does not cover PowerFlex 755 frames 8…10 (p. 5).
• According to the 755TS catalog number explanation, the 755TS comes in frames 1…7 and two voltage classes only: C (400 V AC/540 V DC) and D (480 V AC/650 V DC) (p. 15). The PowerFlex 755 also has 240 V, 600 V and 690 V classes (p. 12); for those drives 750-RM102 gives no 755TS equivalent, so ask Rockwell before planning.
• In the guide, "PowerFlex 755T" is the umbrella name for the whole TotalFORCE family (755TL, 755TR, 755TM, 755TS) (p. 5).

750-RM102 says nothing about the lifecycle status of the PowerFlex 755. To find out whether the catalog you run is still sold, check Rockwell's lifecycle pages or run a lifecycle review.

Why Rockwell positions the 755TS as the next step from the 755

On p. 9, the 755TS brings the TotalFORCE control platform to six-pulse applications, in a familiar package designed to replace the 755. The benefits Rockwell lists include: more precise velocity, torque and position control; adaptive tuning; predictive diagnostics for drive and motor condition; ambient temperatures up to 60 °C; an optional corrosive gas protection (XT) version; CIP Security support; and UL 61800-5-1 certification.

What stays the same

Rockwell calls this a one-to-one replacement (Table 1, p. 9):

Converting the catalog number

P. 10 explains how to derive the 755TS catalog from the 755 catalog:

1. Position 4: change 1 to 2 if corrosive gas protection is not needed, or to E for XT.
2. The EMC filtering / common-mode cap selection becomes J, meaning the drive ships with the common-mode jumpers installed (J is the only code offered on the 755TS, p. 17).

The guide's example: 20G11ND022JA0NNNNN or 20G11ND022AA0NNNNN both become 20G21ND022JA0NNNNN (standard) or 20GE1ND022JA0NNNNN (XT).

What changes

Hardware and installation

• Flange kit for frames 6…7: 20-750-FLNG4-Fx on the 755 (p. 12). For the 755TS, 750-RM102 itself gives two different numbers — 20-750-FLNG4-Fn (p. 15) and 20-750-TFLNG1-Fx (p. 16) — so confirm the kit with Rockwell before ordering. Flange-mount drives have a few mechanical differences (p. 11).
• DC bus bar kit for frame 6…7 AC-input drives without DC terminals: 20-750-DCBB1-Fx on the 755 (p. 12), 20-750-DCBB3-Fn on the 755TS (p. 15).
• A supercapacitor replaces the real-time clock battery; dual gigabit EtherNet/IP ports; frames 1…5 include an EMC C3 bracket; DPI port 2 is in a new location (p. 22).
• The main control board has ENABLE (P7) and SAFETY (P8) jumpers: park P7 when Digital Input 0 on TB1 is used as a hardware enable; park P8 when a safety option is fitted (p. 23).
• Input protection must be reviewed: confirm the supply does not require an SCCR above 100 kA, and review fuses/breakers against 750-TD104, because the 755TS follows UL 61800-5-1, which replaces UL 508 (pp. 10–11).

Applications to rule out first

P. 10 asks you to confirm that the application does not use Logix CIP Motion instructions for permanent magnet motors, and does not use the adjustable voltage mode (common on magnetic stirrers and other non-motor AC loads). "Adj VltgMode" has no 755TS equivalent (Table 9, p. 26).

Ports and option modules

• Port 00 is the drive and its embedded Ethernet, 01–03 are HIM/DPI, option modules go in ports 04…08, port 09 holds application parameters (DeviceLogix, TorqProve, PID), ports 10–11 are primary/secondary motor control and port 12 holds power parameters (Table 3, p. 18). 755TS frame 1 has no ports 07 and 08 (p. 22).
• Each module type is only valid in certain ports — communication modules, for example, only in 04…06 on the bottom row — so check Table 3 before re-arranging.
• The 20-750-APS is not compatible with the 755TS; use the 20-750-TAPS-XT instead. External 24 V control power also requires this module, and because the 755TS takes longer to boot, Rockwell suggests the TAPS-XT where boot time is critical (pp. 10–11).
• Option module function programming does not change; only the drive parameter references used by the module do (p. 38).

Communication

20-COMM modules on the 755 must move to 20-750 option modules (p. 10). Summary of Table 4 (p. 19):

The 20-750-CNETC, DNET and ENETR work with some limitations on explicit messaging. The 755TS embedded Ethernet does not support web pages, peer-to-peer or email (p. 31); for existing peer-to-peer use, Rockwell suggests looking at the 20-750-TLINK-XT, which currently transfers velocity and torque references. ControlNet is Active Mature; Rockwell recommends considering a move to EtherNet/IP (CNET-RM001).

Parameters

Chapter 2 lists three main differences (p. 25):

1. Dynamic Features: Motor Control Mode, Application and Embedded Logic are selected in Device Definition (CCW or Studio 5000) or by parameter from the HIM; each selection loads a new default parameter set after a reset or power cycle. Only parameters used by the selected mode are shown.
2. Port and parameter numbers change almost throughout.
3. The 755 flux vector velocity loop configuration cannot be reused.

Some examples (full tables on the pages shown):

Easy things to miss:

• Motor control mode enumerations change: Induction FV is 3 on the 755 but 4 on the 755TS; Induction VHz goes from 0 to 1 (Table 9, p. 26). Any PLC that writes this value must be changed.
• Application parameters (Process PID, TorqProve, Oil Well Pump) move to port 9, and only one set can be active (p. 27).
• The 16-bit datalinks used with 20-COMM modules — 0:895…0:902 [Data in A1…D2] and 0:905…0:912 [Data out A1…D2] — do not exist on the 755TS; with a 20-750 module, datalinks are selected in the module's host parameters (pp. 34, 40).
• The "Run Forward/Reverse" and "Jog Forward/Reverse" digital input functions have no equivalent; use Run or Jog together with the Fwd/Reverse input (p. 37).
• Speed units, voltage class and duty rating need a reset or power cycle to take effect (p. 35).

Flux vector tuning

Units and control-loop relationships differ, so do not copy flux vector tuning from the 755 to the 755TS (p. 39). Rockwell recommends retuning per 750-AT006, or using the startup wizard in CCW/Studio 5000 (p. 11). For example, 0:636 [Speed Reg BW] is in rad/s, while 10:906 [System BW] is in Hz and drives several other parameters.

DeviceLogix

On the 755TS, DeviceLogix lives in port 9 (enabled with 0:72 [Emb Logic Select] = DLX) and uses tag binding instead of linked parameters (pp. 29–30). The logic transfers by copy/paste or by exporting a .dlr file and importing it, but the tags do not transfer; recreate them in the Tag Editor (pp. 40–44).

Software, firmware and HIM

From Table 7 (p. 24):

Firmware, AOP and EDS files come from the Product Compatibility and Download Center (rok.auto/pcdc) (p. 5). Rockwell recommends the latest versions.

Safety option modules

The 755TS supports the same safety option modules as the 755: 20-750-S, 20-750-S1, 20-750-S3 and 20-750-S4, one module per drive (pp. 18–21). The guide says:

• 20-750-S: no configuration change if it goes in the same slot with unchanged wiring.
• 20-750-S1: its parameters are identical on both drives and must be duplicated on the new drive.
• 20-750-S3 (CIP Safety): in the GuardLogix project the 755 must be removed and the 755TS added; a safety signature or safety lock must be removed before the configuration can be changed.
• 20-750-S4: configured through the AOP and must be replicated; the "host configuration" parameters that set how the drive reacts to safety states have different numbers, and possibly different names, on the 755TS.
• If the existing application used encoder feedback, a 750-series encoder option module is needed.

Rockwell requires the safety application to be revalidated when migrating to a 755TS with a safety option module, and all safety data, including system reaction time, to be reviewed (pp. 11, 21). This article does not state any safety rating; what is achieved depends on the whole system and must be reassessed.

Plant checklist

1. Survey the nameplate: record the full 20G catalog string, frame, voltage, enclosure and input type. Frames 8…10 and voltages other than 400/480 V fall outside 750-RM102.
2. Check the p. 10 conditions: SCCR ≤ 100 kA, input protection, no CIP Motion for permanent magnet motors, no adjustable voltage mode.
3. List option modules in ports 04…08 and any 20-COMM module, and map them using Tables 3–4; watch for the APS, PBUS/PNET series B, flange kits and DC bus bar kits.
4. Back up (p. 24): upload parameters with CCW or Studio 5000 (record them by hand if you cannot go online), label all power and I/O wiring, save network files and PLC programs; export DeviceLogix to .dlr.
5. Network: move IP settings to the new parameters, replace any web or peer-to-peer functions in use, decide the path for ControlNet/DeviceNet.
6. Software: install the right CCW/Studio 5000 and AOP versions; download firmware from the PCDC.
7. PLC and HMI programs: replace the drive module in the I/O tree and review every place that writes parameter numbers, enumeration values or datalinks.
8. Convert parameters: set Dynamic Features first, then work through the Chapter 2 tables; do not copy flux vector tuning.
9. Safety: move the module and wiring, replicate the configuration, set jumper P8, revalidate.
10. Test: tune, then check start/stop, speed reference, datalinks, communication-loss behaviour and every safety function before handover.

Once running, 755TS fault codes (firmware 10 and later) are looked up in the 750-RD102 spreadsheet, no longer in the user manual (Knowledgebase QA77928).

TDL plans and carries out Rockwell Automation upgrades. Need an engineer on site: request support.