LTI Motion ServoOne PROFIBUS/PROFINET Troubleshooting and Replacement

LTI Motion ServoOne PROFIBUS/PROFINET Troubleshooting and Replacement

System Overview and Security Boundaries

The ServoOne series servo drives (including single axis systems, multi axis systems, and ServoOne junior) support both PROFIBUS and PROFINET fieldbus systems. PROFIBUS is based on RS-485 and adopts a master-slave polling mechanism, which is suitable for manufacturing and process automation; PROFINET is based on Ethernet TCP/IP and supports real-time (RT) and synchronous real-time (IRT), making it suitable for high dynamic motion control. Both follow the PROFIdrive device specifications to ensure consistent behavior of drivers from different manufacturers on the bus.

Safety always comes first. There is a dangerous voltage of 230V/460V inside the drive, which may still be charged within 10 minutes after power failure. Rotating components, automatically starting drivers, hot surfaces, and electrostatic discharge can all cause injury. Only personnel with electrical engineering qualifications and familiarity with accident prevention regulations such as BGV A3 can operate. Pacemakers, metal implants, and hearing aid wearers must stay away from the installation, maintenance, and operation areas of the drive system. Before debugging, it is necessary to read the relevant equipment manual, check the parameters, and prevent the driver from losing control due to changes in bus parameters.

PROFIBUS installation and address setting

The PROFIBUS interface is located on X14 of the ServoOne driver and is a 9-pin D-Sub socket that complies with the EIA-485 standard. Pin definition: 3 is B/B '(red, RxD/TxD-P）， 8 is A/A '(green, RxD/TxD-N）， 5 is DGND, 6 is VP (+5V terminal resistor power supply). Terminal resistors must be connected at both ends of the bus, with typical values: Ru=390 Ω connected to VP, Rd=390 Ω connected to DGND, Rt=220 Ω connected across pins 3 and 8. Use Siemens 6GK1500-0FC10 bus connector (with axial cable outlet) and 6XV1830-0EH10 standard cable. The maximum cable length depends on the baud rate: 9.6 to 187.5 kbit/s is 1000m, 500 kbit/s is 400m, 1.5 Mbit/s is 200m, and 3 to 12 Mbit/s is 100m. Up to 32 bus users can be extended into a tree structure through repeaters.

There are three ways to set the address: encoding switches S1 and S2, bus address parameter P-0918 in DriveManager 5, and integrated control unit. The encoding switch is used for single axis and multi axis systems, with a setting range of 0 to 125, where S1 is high and S2 is low, for example, address 12, S1=1，S2=2。 When using parameter P-0918, the encoding switch must be set to greater than 125 (such as 0xFF) to take effect. The integrated control unit selects "Fb" through buttons T1 and T2, sets the hexadecimal address, and saves by pressing T1 and T2 to "ok". After any address change, the device must be restarted. The address must be unique and cannot be duplicated.

PROFIBUS LED diagnosis: H1 yellow indicates cyclic data exchange, H2 red and H3 green indicate status. Power on self-test: If both H2 and H3 light up at the same time, it is reset. If H2 lights up and H3 lights up, it is ASIC RAM testing. If H2 lights up and H3 lights up, it is testing completion. Diagnostic status: H2 off and H3 flashing indicate "seeking baud rate", H2 off and H3 constantly on indicate waiting for parameter data, H2 off and H3 off indicate communication but no Class 2 connection. H2 flashes twice and stops once to indicate 'clear state', flashes twice to indicate parameter data error, and flashes three times to indicate configuration data error. H2 flashes 3 times and H3 goes out, indicating data exchange with Class 2 connection. H1 lights up during normal cyclic data exchange.

PROFINET Installation and Diagnosis

The PROFINET interface uses RJ45 sockets X47 and X48, which comply with the EIA/TIA-568B standard. Pin 1 is Tx Data+(white/orange), 2 is Tx Data - (orange/white or orange), 3 is Rx Data+(white/green), and 6 is Rx Data - (green/white or green). Support automatic negotiation, automatic crossover, and automatic polarity. PROFINET supports line, star, tree, and ring topologies, and integrated switches do not require additional network components. The cable uses standard Ethernet jumpers (such as S/FTP Cat. 5e) with a maximum length of 100m.

PROFINET LED diagnosis: H16 red and H17 green. Power on self-test: If both lights are on at the same time, it means reset. If H16 lights up and H17 goes out, it means device testing. If both lights are on at the same time, it means testing is complete and the bus is ready. Diagnostic status: When both lights are on simultaneously, it indicates that the bus is ready but there is no cyclic data exchange; H16 off and H17 on indicate that the bus is ready and data exchange is in a loop; H16 is on and H17 is flashing, indicating that PROFINET software is being loaded from the drive memory; H16 is turned off, H17 is lit with a short interrupt indicating RT Class 1 cyclic data exchange. The green LED on the RJ45 socket indicates Link/Activity (off=no connection, on=connected but no data, flashing=data exchange), and the yellow LED indicates RUN (off=initialization, flashing=Pre Operational, single flashing=Safe Operational, on=Operational).

GSD/GSDML configuration and cyclic data

PROFIBUS uses GSD files (Universal Station Description), while PROFINET uses GSDML files (XML format). When configuring, the corresponding files need to be imported into the main site engineering tool. The GSD file of ServoOne can be downloaded from the official website of LTI Motion. The naming convention for GSDML files is as follows: "GSDML-V2.3-LTI-SeroOne-20130515. xml". Starting from version "GSDML-V2.3-LTI-SeroOne-2017013.1. xml", the module structure has been updated to comply with PROFIdrive line rules: module IDs are from 0x1001 to 0x1070, and submodule IDs are from 0x0001 to 0x0070. For example, the module ID of standard message 1 is 0x1001, the submodule ID is 0x0001, and 2 input words/2 output words.

Standard Message (PPO) is based on PROFIdrive. ServoOne supports: Standard Message 1 (speed control, 2/2 words), Standard Message 2 (speed control, 4/4 words, PROFINET only), Standard Message 3 (isochronous speed control, 5/9 words, PROFINET only), Standard Message 5 (isochronous DSC, 9/9 words, PROFINET only), Standard Message 7 (drive set selection, 2/2 words), Standard Message 8 (positioning, 5/5 words), Standard Message 9 (positioning, 6/5 words). User defined messages can be freely mapped through parameters P-0915 (write) and P-0916 (read), and the signal list can be found in P-1284 and P-1285. Each message can contain PKW parameter channels and PZD process data channels.

Non cyclic data and parameter access

Besides cyclic data, PROFIBUS/PROFINET supports non cyclic parameter access. PROFIBUS uses DP-V1 service, and through SD2 messages, the data units include Req.id, Slot, Index, Length, and UserData. PROFIdrive specifies an Index of 47 (0x2F) for parameter access. Read and write requests are completed through Write.req and Read.req, and the response may be negative. PROFINET uses "Record Data CR" for reading and writing, with an Index of 0x002E. The data format is "Base Mode Parameter Access", which includes request reference, request ID, axis number, number of parameters, attributes, number of elements, parameter number, sub index, format, number of values, and value/error code. Request ID: 1 is the request parameter, 2 is the modification parameter. Response ID: Positive response is 1 or 2, negative response is 0x81 or 0x82. Error codes such as 0x00 parameter not allowed, 0x01 parameter value unchangeable, 0x02 out of range, 0x03 sub index error, 0x05 data type error, etc.

Operation mode and state machine

ServoOne supports speed control, position control, jog, isochronous speed control (application class 4), DSC position control (application class 4), and interpolation position control (application class 5, only PROFINET). Select through parameters P-0300 (control mode) and P-0301 (reference value generation mode). Standard messages 1, 2, and 3 are automatically set to speed control, while others are set to position control. The state machine conforms to PROFIdrive: system initialization → not ready → disable switch → ready → already on/off → control activation → quick stop activation → fault response → fault. The control word STW1 has bit 0 as the switch, bit 1 as the prohibition of coasts top, bit 2 as the prohibition of quick stop, bit 3 as the control enable, bit 4 as the ramp generator, bit 5 as the enable ramp, bit 6 as the activation reference value, bit 7 as the fault confirmation, bits 8/9 as the jog, bit 11 as the return to zero, and bit 13 as the absolute/relative positioning. The status word ZSW1 has bit 0 indicating readiness, bit 1 indicating power level activation, bit 2 indicating operation enable, bit 3 indicating fault, bit 4 indicating prohibition of coasts top, bit 5 indicating prohibition of quick stop, bit 6 indicating switch prohibition, bit 7 indicating warning, bit 8 indicating speed error/tracking error, bit 10 indicating target arrival, and bit 11 indicating completion of zeroing.

Watchdog and Sign of Life monitoring

Watchdog monitoring loop communication. If the driver does not receive a loop message within the set time of parameter P-1283 (COM_SP_BUS_Timeout), the watchdog triggers an error (32-1). P-1283 defaults to 5000ms and is disabled if set to 0. Sign of Life (SOL) monitors the synchronization of master-slave loop counters, in compliance with PROFIdrive 4.2. Set the allowed number of SOL errors for parameter P-0925 (COM_CN_Sign_of_life_imit), with 0xFFFF disabled (default). Every time a loop message is received, bits 12-15 of status word 2 increase; The bits 12-15 of control word 2 are incremented by the main station. If the counter does not match, the error counter P-1296 increments by 10; If matched, decrease by 1. When the error counter is ≥ 10 × P-0925, an error (32-03) is triggered and bit 4 of P-0953 is set. After stopping and restarting the loop communication, the error counter is reset to zero and the warning bit is reset.

Common troubleshooting

Bus communication failure: Check if the PROFIBUS address is unique, if the encoding switch matches parameter P-0918, if the terminal resistance is only activated at both ends, and if the cable length and baud rate match. PROFINET checks IP address, subnet mask, gateway (P-1290/P-1291/P-1295), device name (P-1289), and LED status. Check if the GSD/GSDML file is imported correctly and if the module ID matches the submodule ID.

Watchdog timeout: Check if the main station cycle is less than the set value of P-1283, increase P-1283 or optimize the main station program. Check cable shielding and grounding to ensure no interference. If P-1283 is 0, the watchdog is disabled, but it is usually not recommended.

Sign of Life error: Check if the main station correctly increments bits 12-15 of control word 2. If the main station does not implement SOL, set P-0925 to 0xFFFF and disable it. If implemented, check the P-0925 threshold and P-1296 error counter. After an error response, it is necessary to restart the loop communication or reset.

Parameter access failed: Check the PKE, SUB, and LEN formats of the PKW channel. Do the request ID and response ID match. Error codes such as 0x00 indicate parameter number not allowed, 0x02 indicates out of range, and 0x05 indicates data type error. Confirm whether the parameters are writable and in the correct operating mode. Non circular access: Note that DP-V1 has a Slot of 0 and an Index of 47.

Abnormal position control: Check the timing of control word bits 4, 5, and 6. Position 4 activates the ramp, position 5 enables it, and position 6 activates the rising edge positioning. If bit 13 is set, the new reference value will take effect immediately. Returning to zero position 11, the rising edge is activated, and the status word bit 11 indicates completion. Check the P-1255 reference tag configuration and whether the digital inputs ISD05/ISD06 are set to Probe.

Drive not starting: Check for STO/ENPO signal. The state machine requires setting the safety stop first, and then setting the ENPO rising edge. Control the placement of characters 0, 1, 2, and 3 in order. Check the automatic start setting of P-0144. Check the fault code and read it through P-0945/P-0947/P-0949.

Shutdown replacement and parameter migration

When the original ServoOne driver or fieldbus module is discontinued and replaced, it is necessary to check the firmware version (this manual applies to 4.20 and above), bus type (PROFIBUS or PROFINET), message type (standard or custom), and GSD/GSDML file version. After replacement, import GSD/GSDML again, configure the same message, set the same address (PROFIBUS) or device name/IP (PROFINET). Parameter migration can be done using DriveManager 5 to export/import parameter sets, or by reading and writing them one by one through the PKW channel. Key parameters: P-0915/P-0916 mapping, P-0918 address, P-0922 message selection, P-1258 control mode, P-1283 watchdog, P-0925 SOL threshold. If replaced with different series, the current loop, speed loop, and position loop need to be readjusted, and the STO function needs to be retested. For PROFINET, please note that the GSDML module structure has changed, and the old module ID may need to be changed to a new ID (such as the 0x1001 series). After replacement, cyclic data testing, watchdog testing, and SOL testing must be conducted to ensure system stability.