| Electronics > Beginners |
| Variable frequency drive control via Modbus, register read/write limit? |
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| V_King:
Hello, I am after variable frequency drive, to control the electric motor RPM via RS485(Modbus). There is a Bosch Rexroth EFC5610 VFD, which I really like, it has an in-build motor thermal protection, but in Modbus communication description it warns that the registers read/write limit is only 150000 times/register. I will be changing the frequency registers frequently and that worries me. I had a look at other VFDs (Siemens V20, Schneider ATV12, Parker AC10) and none of their manuals mention the Modbus communication limits for read/write cycles per register. A lot of the industrial electronics seem to have unwritten defaults and I wonder whether the 150k cycles mentioned by Bosch is default for majority of VFDs, or is it just the big drawback of the EFC5610 VFD? Thanks |
| Kalin:
I have never hear of that with other drives and never run into a failure to write to memory with any drives I have used even the ones that use an eeprom for storing parameters. How often do you plan on writing to this value? Sent from my SM-G965W using Tapatalk |
| V_King:
--- Quote from: Kalin on March 03, 2019, 05:35:30 pm ---... How often do you plan on writing to this value? --- End quote --- The motor is for a small test rig, to test parts. The test would use up to 10 different frequencies (not pre-set ones). The test could be run to to ten times an hour, 8 hours a day. So pretty much in theory, the registers would be shot within a year :( I would have thought the read/write count would be much greater, considering todays interconnected controls in the industrial environment. |
| Kalin:
Would you consider another manufacturer or have you already purchased the drives? It might be a typo because that is not really an acceptable number for any application I can imagine for a VFD. Sent from my SM-G965W using Tapatalk |
| V_King:
--- Quote from: Kalin on March 03, 2019, 08:56:58 pm ---Would you consider another manufacturer or have you already purchased the drives? It might be a typo because that is not really an acceptable number for any application I can imagine for a VFD. --- End quote --- I was not far from placing the order, luckily found the info in time. I just wanted to make sure it does not apply universally throughout VFDs before considering different manufacturer. I do not think it is a typo, because the read/write limit is throughout a number of revisions I checked and they have warning in a number of manual sections. |
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