LTI Motion ServoOne PROFIBUS/PROFINET Troubleshooting and Replacement

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.