wlewis Posted November 7, 2018 Posted November 7, 2018 We have the following physical setup: PowerPMAC CPU in UMAC chassis ACC-5E3 MACRO fiber link 8 Axis MACRO CPU ACC-24E2S Stepper drive With this configuration, and the default ms0, mi903 of 2258, we cannot modulate the stepper speed very well. As we increase the open loop output (#1 out ), the motor jumps from stopped to rotating at a speed equivalent to a step output frequency of 150 steps/second. This occurs when the output magnitude reaches 1. It appears that with this configuration, the stepper speed is limited to discrete values. The next step is a motor speed of around 300 steps/second. Changing ms0, mi903 to 2298 (increasing PFM clock divider from 2 to 7) reduces the lowest achievable speed, and reduces the increments for each speed change. The ACC-5E3 manual states that only the high 16 bits of Gate3.MacroOutA[j][2] are transferred across the MACRO link. Is there a configuration change we can make on the ACC-24E2S other than the PFM clock divider, to allow better speed modulation? What I would like is for the stepper speed to respond correctly to fractional changes in the motor output command.
steve.milici Posted November 9, 2018 Posted November 9, 2018 I think the following "outline" would be the best approach: 1. Enable MLDT mode MI161 – 168, writes to C register once at power on and disable write to C register. 2. Use MI19 = 0 (xfer phase rate). It’s done in background and not phase interrupt but should be fast enough. 3. MI20 (MI21-68 xfer enable) & 4. MI21 – 68 (24 bit xfer format) There’s an X or Y 24 bit transfer FROM and TO format See the "old" MACRO SRM for details on these: http://www.deltatau.com/manuals/pdfs/MACRO%20SRM.pdf?id=635787783273153363
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