text: <s>[INST] MULTIPLLE PF400 ON MODBUS I HAVE 3 PF400 DRIVES ON MODBUS. THESE DRIVES ARE TO BE INDEPENDENTLY STARTED AND STOPPED . THE DRIVE NODES ARE SET TO 19.2KB SPEED . THE MODBUS MASTER IS MICROLOGIX1400 AND ON CH0. FOR MAINTENANCE PURPOSES, SOMETIMES I HAVE TO ELECTRICALLY ISOLATE A DRIVE. WHEN I ISOLATE A DRIVE( POWER DOWN) THE MESSAGE INSTRUCTION FAULTS AND LOSES COMMUNICATION TO THE OTHER 2 DRIVES. TO EACH DRIVE, IAM SENDING IN/OUT 6 MESSAGE INSTRUCTIONS ( FOR STATUS READ, SPEED REFERENCE, AND OTHER PARAMETER READS). HERE, I CANNOT DO A BROADCAST COMMAND USING REGISTER 16 IN MODBUS, SINCE EACH OF THE DRIVE ARE TO BE STARTED AND STOPPED INDEPENDENTLY AND THE SPEED REFERENCE TOO SHALL VARY. PLEASE HELP ME FIX THIS PROBLEM. [/INST] If you post the program (or at least the Message instruction control portion), a Forum member may be able to help you. There is no reason that you cannot write a program that communicates successfully to 1, 2, or 3 drives, even if one or more is powered down. You can write a fully functional Command / Status / Monitoring application over Modbus to PowerFlex drives with only four messages per drive. Message 1: Write Command and Reference.Message 2: If Command/Reference fails due to Comms Timeout being nonzero, write Comms Timeout value.Message 3: If Command/Reference succeeds, read Status / Feedback.Message 4: Read Parameters using DPI Object Scattered Read function. Repeat for each drive. If any of the four messages fails on a Timeout, the message sequence should jump to the next drive's Messages. \\n </s>