SIMOREG 6RA7091 T300 Technology Board: F122, F123, F103 Fault Diagnostics and Field Repair

The SIMOREG 6RA70 series DC drive family from Siemens uses a slot-based modular control architecture in which the T300 technology board implements application-specific control laws (hoist positioning, angular synchronism, register control, winder control) on top of the standard armature/field control loop resident in the basic unit. When a T300-equipped 6RA7091 drive reports F122, F123, or F103, the alarm almost always points to one of three physical causes: (a) the dual-port-RAM handshake between the T300 and the CUD1 basic board has stalled, (b) the technology-slot analog or digital I/O is outside its measurement range, or (c) the underlying power-section measurement chain the technology board depends on for closed-loop operation has developed a fault. This reference consolidates the field procedure for isolating those three alarms on a 6RA7091 chassis, the parameter ranges that must be inspected on the T300, and the documentation set that must be ordered before a service call is opened. The information is consistent with the SIMOVERT MASTERDRIVES Vector Control Compendium VC34 and the SIMOREG 6RA70 Parameter Description manuals published by Siemens A&D.

1. SIMOREG 6RA70 Architecture and T300 Slot

The 6RA7091 is the largest frame in the SIMOREG 6RA70 digital DC drive family. It is a fully-digital three-phase, fully-controlled thyristor armature converter with a separately-excited field supply, intended for 6-pulse or 12-pulse (parallel) operation up to approximately 3000 A armature current depending on firmware derating and ambient temperature. The basic unit — CUD1, catalog suffix -LA for the standard unit, -MA for the motion-control variant — contains the armature control firmware, the field control firmware, the analog I/O, and the two serial interfaces (RS485 and RS232) used for the OP1S commissioning panel and the SIMOVIS/STARTER service tool.

The T300 is inserted in the technology slot located on the front of the electronics box, immediately behind the parameter card. It carries its own microprocessor (Intel 80C166-class), its own firmware ROM (e.g. MS340 angular synchronous, MS370 hoist, MS390 register control), and its own parameter memory (typically 4 kB of non-volatile storage). The basic unit and the T300 communicate through a dual-port RAM (DPR) mapped into parameter ranges H... and P... on the T300 side and r.../n... on the CUD1 side. Communication is mandatory: if the DPR handshake fails, the basic unit cannot close the speed or torque loop through the technology variables and the drive is forced off-line with one of the technology-board alarms listed in Section 5.

2. Technology Board Variants and ROM Identification

The T300 designation is generic; the firmware loaded on the board determines the actual control law and the parameter subset visible to the user. The most common firmware releases shipped on a 6RA7091 technology board are listed in the table below. The ROM version is read from the T300's n0499 register using a serial terminal at 9600-8-N-1 on the T300's diagnostic port (X105, the 9-pin sub-D on the front edge of the board).

Because the parameter meaning changes with the ROM, an alarm that reads F122 on an MS330 may require a different physical wiring verification than the same F122 on an MS340. Always confirm the ROM name (printed on the EPROM label of the T300) before consulting a parameter manual. The OP1S panel will display the ROM identifier on power-up for ~3 s as SW: MS34x Vx.xx in the lower status line.

3. Required Documentation Set

Before opening a service call, the following documents must be available on site. The T300 is shared hardware between the SIMOREG DC drive and the SIMOVERT MASTERDRIVES VC family, so the technology-board documentation is in the Masterdrives compendium, not the SIMOREG 6RA70 manual. Order numbers in the Siemens EWS system are listed for reference; availability has migrated to the Industry Online Support (SIOS) portal.

4. Parameter Structure on the T300

The technology board exposes its variables under a parallel numbering scheme that is independent of the CUD1 numbering. Knowing which range to read is essential because OP1S and SIMOVIS both expect the user to select the parameter source before browsing. The mapping is summarized in the table below.

Two important restrictions apply:

1. Parameters in the H range are only meaningful for the active ROM. Reading H1567 on an MS330 returns 0: undefined with status word bit 0 set; the F-codes do not raise, but the parameter is dormant.
2. The T300 is configured at the factory with default BICO connectors that assume a 1.0 V× (5000 min⁻¹) analog tachogenerator and a 1024-pulse incremental encoder. If a different feedback device is installed, parameters n040 (tacho scaling) and n041 (encoder pulse count) must be set before any H-parameter commissioning; otherwise F123 will trip on the first ramp.

5. Fault Code Definitions

The three alarms the field engineer is concerned with are summarized below. F-codes are latched in the technology board's fault memory (H0700 area) and are mirrored into the CUD1 status word; both must be cleared to restart the drive.

5.1 F103 — Power-Section / Measurement-Circuit Fault

F103 is a CUD1-side alarm that has multiple root causes. The exact sub-code is read from r947 on the CUD1, which is a 16-bit word with bit meanings that vary by firmware. On a T300-equipped drive, the most common path to F103 is:

1. Armature current measurement chain: The three current transducers (LEM LA305-S or equivalent) on the 6RA7091 are not sitting at the correct zero offset. With the contactor open, r019 (Ia actual) should read 0.0 A ± 1 % of rated. A reading > 2 % trips F103 within 80 ms of the on command.
2. Field-current measurement chain: When the drive is configured for field-weakening (P082 = 1) the field current feedback is monitored continuously; loss of the field-current sense resistor (0.5 Ω, 60 W) trips F103 sub-code 7.
3. Technology board handshake loss: If the T300 stops updating the DPR, the CUD1 raises F103 as a safety response (sub-code 14) because the technology control law can no longer influence the torque loop. This is the most common cause of F103 on a drive that also reports F122/F123.

5.2 F122 — T300 Communication Alarm

F122 indicates that the DPR handshake between the CUD1 and the T300 has failed. The T300 sends a keep-alive token to the CUD1 every 5 ms; if two consecutive tokens are missed, F122 is raised and the drive disables the on command. Root causes are listed in order of frequency on a 6RA7091:

5.3 F123 — T300 Internal Task Overflow

F123 is the technology board's own alarm, raised when one of the internal time slots in the T300 firmware has overrun. The 80C166 processor runs the angular-synchronism, hoist, or register control block at a 1 ms cycle, the BICO dispatcher at 5 ms, and the parameter handler at 20 ms. The most common sub-codes (read from n0490) are:

6. Field Commissioning Procedure

The following procedure brings a T300-equipped 6RA7091 from a power-up state to a verified F122/F123/F103-free run. The procedure assumes a 6-pulse, single-armature drive with a 1.0 V× analog tachogenerator, a 1024-pulse incremental encoder on the motor shaft, and an MS340 angular-synchronous ROM (the most common ROM shipped in a 6RA7091 retrofit).

6.1 Prerequisites

1. Confirm that the Compendium VC34 (6SE7080-0QXxx) is on site and is at the same revision as the CUD1 firmware (read from r060 on the CUD1).
2. Confirm the Masterdrives Compendium is the one for the active ROM. Cross-check the ROM version in n0499 with the EPROM label on the T300.
3. Verify the OP1S panel firmware is at least V2.0 (reads from n0498 on the panel itself). Earlier OP1S firmware will not display the H range correctly and will report a generic "rEAd FAIL" when browsing T300 parameters.
4. Measure the 5 V supply on the T300 test pins TP1/TP2. The voltage must be 4.95 V — 5.05 V. A reading below 4.85 V indicates a power-supply problem on the CUD1 that will manifest as F122 or F123 under load.
5. Verify the EPROM is fully seated; a partially-seated EPROM will power up but F122 will be raised at first DPR access because the firmware checksum fails.

6.2 Step-by-Step Diagnostic

1. Power up with the contactor open and the on command off. Read r060 (CUD1 firmware), r061 (T300 firmware via the CUD1 mirror), and n0499 (T300 firmware raw). All three must be non-zero. If r061 = 0, the CUD1 cannot see the T300; check the X120 ribbon cable between the basic unit and the electronics box backplane.
2. Read the fault memory before clearing. From the OP1S, press MENU → DIAG → FAULT → READ. Note F103, F122, F123, and any associated r947, r949, r950 sub-codes. Photograph the screen if you do not have a SIMOVIS connection.
3. Clear the fault memory. Apply +24 V to terminal X101.4 (CUD1 reset input) for at least 1.5 s, then release. Wait 5 s. The OP1S should display RDY in the upper status line and no code in the alarm line. If any code remains, repeat with a longer reset (3 s) and check the wiring.
4. Verify the analog I/O on the T300. With the on command off, drive the analog input X106/1 (master setpoint, ±10 V) to 0 V, then to 5 V, then to 10 V. The corresponding T300 connector value (P652 or P654, depending on ROM) must track within ±10 mV. A tracking error > 50 mV indicates a damaged input op-amp on the T300, which must be replaced at the board level.
5. Verify the encoder interface. Rotate the motor shaft by hand at approximately 1 rps. The T300 position register (r015 on MS340) must increment by the number of pulses per revolution set in n041, in the correct direction for the A/B phasing. If the register increments in the wrong direction, swap the A and B wires on X107.
6. Run a no-load ramp. Issue the on command from the OP1S (PROG → CONTROL → ON). Set n008 (rated speed) to 10 % of rated and command a 5 s ramp from 0 to 10 %. The drive should reach 10 % speed without F103, F122, or F123. If F123 sub-code 1 raises, see Section 5.3 note.
7. Run a load step. With the motor coupled, apply 50 % rated load step (use a second motor as a generator with a resistor bank). Monitor r019 (armature current), r022 (speed), and r015 (angular error on MS340). The angular error must remain below 50 pulses; a steady-state value > 200 pulses indicates the gear ratio (H1620/H1621) is set incorrectly.
8. Save to the parameter card. From the OP1S, MENU → PARAM → SAVE. This writes all T300 H-parameters and CUD1 n-parameters to the removable parameter card on the front of the electronics box. Without this step, a power loss or a hot-swap of the CUD1 will revert the drive to factory defaults, and the next power-up will trip F122.

7. Verification and Acceptance Test

The drive is considered commissioned and free of F103/F122/F123 when the following matrix is satisfied. Each cell must be checked off on the commissioning sheet, with the corresponding r/n/H readback value noted. Acceptance is signed by the customer witness.

8. Parameter Maps and BICO Wiring

The BICO connectors below are the minimum set that must be wired for a standard MS340 angular-synchronous retrofit. The list is a starting point and is not exhaustive; the full set is in the Compendium VC34, Section 8 ("Technology Board BICO").

The connection from T300 to CUD1 (U256 in the example) is what the T300 firmware uses to add a corrective angular term to the speed setpoint. If U256 is left at 0 (the default), the T300 will run its control law internally but the CUD1 will never see the correction; the drive will appear to operate normally with the technology board disconnected, and F122/F123 will not trip — but the synchronization will be absent. This is the most common commissioning error: the panel shows no alarms, the customer signs acceptance, and the system fails at the first product run.

9. Troubleshooting Matrix

The following matrix links the most common field symptoms to the corrective action. Read left to right; the action column assumes the preceding columns have been verified.

10. Field-Repair Limits

On a 6RA7091 the T300 board is treated as a line-replaceable unit (LRU) by Siemens. Field repair is limited to:

• Reseating the board in slot 2 (4 × M2.5 screws, 0.4 N·m torque).
• Replacing the EPROM (27C256, 150 ns or faster) when the ROM version is wrong and a known-good binary is available in the parameter card.
• Cleaning the X120 ribbon connector with isopropyl alcohol and a non-abrasive swab.
• Replacing the lithium backup battery (type CR2032, on the rear of the parameter card) if the drive forgets the H-parameters on power-down. Battery life is approximately 5 years at 25 °C.

All other faults require board-level replacement. The DPR ASIC is not socketed, the analog input op-amps are surface-mount, and Siemens does not publish the schematics to the field engineer. Spare T300 boards must be ordered with a known-good EPROM and a factory-loaded parameter set; a factory-default T300 will not talk to a commissioned CUD1 without the parameter set being reloaded from the parameter card on power-up.

11. Documentation and Firmware Versions

The information above is current with the following Siemens document revisions. Newer revisions may add parameters; older revisions will not include the F118/F119 alarms. Always cross-check the OP1S SW: line against the Compendium revision in your binder.

Updated revisions are published on the Siemens Industry Online Support portal; searches for 6RA7091, 6SE7080, and Masterdrives Compendium will return the latest files. The Compendium is the only document that is updated when a new ROM is released; the 6RA70 manuals are not re-issued for T300 changes.

12. Summary of Corrective Actions

For a 6RA7091 reporting F122, F123, and F103 together, the order of operations is fixed and must not be varied:

1. Read r947, r949, r950, n0490, n0499, and r002 to determine the originator of each alarm.
2. If r947.14 = 1, the T300 handshake is the root cause; isolate F122/F123 before touching the power section.
3. For F123 sub-code 1, set n1610 (encoder pre-divider) and verify n041 (encoder pulse count) is non-zero before further testing.
4. For F122, reseat the T300, then re-test the 5 V supply on TP1/TP2, then replace the T300 if the alarm persists across two power cycles.
5. For F103 sub-code 14 (T300-induced), the F103 will clear automatically once F122/F123 is resolved. Do not chase F103 first.
6. Save the parameter set to the parameter card after every change; an unsaved change will be lost on the next power cycle and will re-trip F122.

Following this sequence resolves the three alarms in approximately 70 % of field cases without a T300 replacement. The remaining 30 % are split between a DPR ASIC failure (replace the T300) and a CUD1 firmware mismatch (reflash the CUD1 with the matching CUG file). A current-trace on the X120 ribbon and a 5 V rail check on TP1/TP2 will distinguish the two without further disassembly.