Fuji Electric FRENIC-VG Series - Chapter 5: USING STANDARD RS-485

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CONTENTS
Chapter 5 USING STANDARD RS-485
5.1 Standard RS-485 Communications Ports.................................................................................................. 5-1
5.1.1 RS-485 common specifications.......................................................................................................... 5-2
5.1.2 Terminal specifications for RS-485 communications ........................................................................ 5-3
5.1.3 Connection method ............................................................................................................................ 5-4
5.1.4 Communications support devices ...................................................................................................... 5-6
5.1.4.1 Converters .................................................................................................................................. 5-6
5.1.4.2 Cables......................................................................................................................................... 5-7
5.1.5 Link functions .................................................................................................................................... 5-7
5.1.5.1 Link command permission selection.......................................................................................... 5-7
5.1.5.2 Link edit permission selection.................................................................................................... 5-8
5.1.5.3 S range option priority ............................................................................................................... 5-8
5.1.6 Referencing and changing data .......................................................................................................... 5-9
5.1.6.1 Write restrictions for function codes .......................................................................................... 5-9
5.1.6.2 Negative response and error response...................................................................................... 5-10
5.1.6.3 No response.............................................................................................................................. 5-10
5.1.7 RS-485 function codes..................................................................................................................... 5-11
5.1.7.1 Response interval time (H39)................................................................................................... 5-11
5.1.7.2 Disconnection detection time (H38) ........................................................................................ 5-12
5.1.7.3 Character timeouts ................................................................................................................... 5-12
5.1.7.4 Timeouts on the master side..................................................................................................... 5-12
5.1.8 Host side procedures ........................................................................................................................ 5-13
5.1.8.1 Read procedure ........................................................................................................................ 5-13
5.1.8.2 Write procedure........................................................................................................................ 5-14
5.1.9 RAS.................................................................................................................................................. 5-15
5.1.9.1 Communication errors.............................................................................................................. 5-15
5.1.10 Communication error measures ....................................................................................................... 5-18
5.2 Fuji General-purpose Communications .................................................................................................. 5-19
5.2.1 Message format................................................................................................................................ 5-19
5.2.2 Transmission frame.......................................................................................................................... 5-19
5.2.3 Standard frame ................................................................................................................................. 5-20
5.2.4 Option frame .................................................................................................................................... 5-23
5.2.5 Negative response frame.................................................................................................................. 5-27
5.2.6 Field descriptions ............................................................................................................................. 5-28
5.2.6.1 Data field.................................................................................................................................. 5-28
5.2.6.2 Sum-check field ....................................................................................................................... 5-29
5.2.7 Communication examples................................................................................................................ 5-29
5.2.7.1 Standard frame ......................................................................................................................... 5-29
5.2.7.2 Option frame ............................................................................................................................ 5-30
5.2.7.3 ASCII code table...................................................................................................................... 5-31
5.2.7.4 Program example ..................................................................................................................... 5-32
5.3 Modbus RTU .................................................................................................................
......................... 5-33
5.3.1 Message format................................................................................................................................ 5-33
5.3.2 Transmission frame.......................................................................................................................... 5-34
5.3.2.1 Reading function codes............................................................................................................ 5-35
5.3.2.2 Writing single function codes................................................................................................... 5-36
5.3.2.3 Writing multiple function codes............................................................................................... 5-37
5.3.2.4 Maintenance code .................................................................................................................... 5-38
5.3.2.5 Error response .......................................................................................................................... 5-39
5.3.3 Error checking.................................................................................................................................. 5-40
5.3.3.1 CRC-16 .................................................................................................................................... 5-40
5.3.3.2 CRC-16 algorithm.................................................................................................................... 5-41
5.3.3.3 CRC-16 calculation example ................................................................................................... 5-42