smiffy

The master uses function codes 5, 6, 15 & 16 to send data to the slave.
Function code 5 allows the master to write a single coil (address 00001->) to the slave device
Function code 15 allows the master to write multiple coils (address 00001->) to the slave device
Function code 6 allows the master to write a single holding register (address 40001->) to the slave device
Function code 16 allows the master to write multiple holding registers (address 40001->) to the slave device

So you fixed the previous problem that you had?

i am use cpu 417 and conected rs485 by 6es7138-4df11 to 3 slaves abb acs550 motor driver.

comunicate with fc03 (s-send) and fc04 (resieve)

by function code 03 i perfect read 12 registers status words of each drv. (40001-40012) and store in db.

by function code 06 i perfect write one register ( control word) (run\stop) on each drv.

and second request by function code 06 i perfect write one register ( reference) (speed) on each drv.

this week i tried to use f.code 16 to write same 2 registers in (40001-40012) by one request.  but  it stop work. (plc is run but no tx\rx). may be it because the register 40004 is status word and it reading only.  i get done with error bit .

when i use f.code 16 i only insert row of "n registers" i need to write. and change f.code .

second i dont understand the lens of block. in data sheet of modbus card writed the lens of conection is only 6 bytes. in fc16 writed  >6 bytes what is mean? if i set bigger then 6 it stop work.

what i am doing wrong?

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Split from Modbus Holding Registers.

Hello Kaulquappe.

pdf file is efb protocol for abb driver. on page 19 is f.codes supported by abb and pages 24-25 is registers i read\ write.

we have 50 abb drivers connected by profi-bus. registers 5310-7 are registers for control all driver functions. in this 8 registers you can set all parameters you want to change in process.  like reduce output voltage or set new protect currect. like we have diffrent motors connected to one driver, and each time you need set new protect current. this work perfect on profi-bus. now i try to start use modbus to same work.

maybe it not work for modbus. i am new on modbus protocol ( starting to learn this protocols)

so i get error bit, because the registers is read only?

hello Kaulquappe.

thanks for help. i understand my mistake. when i use f.code 03\06 the len is 6. when i try f.code 16 the len should be difrent. in my project, first request is f.code 03 (12 registers). second req is f.code 16 (2 reg). but the problem i set 10 on len block leg. and is not compatible for f.code 03. becose that i get error bit.  so i change for f.code 03 is len 6 and for f.code 16 len 10. work perfect.

[snip]

thanks