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MACRO Ring State After Watchdog


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The User Manual says “The processor stops operating and will not communicate. All Servo, MACRO, and I/O IC’s are forced into their reset states, which force discrete outputs off, and proportional outputs (DAC, PWN, PFM) to zero-level.”


Does this mean:

- The PMAC card will immediately send out commands onto the ring to disable all amplifiers and to set all command values to zero?

- The PMAC card, after the reset commands, will not continue to send out any data on the MACRO ring?

- The PMAC card, after the reset, will continuously send out the reset states (disable all amplifiers and set all command values to zero) on the MACRO ring?

- The amplifiers we have attached to the MACRO ring immediately shut down if they do not receive MACRO commands addressed to the particular amplifier within each millisecond; should I expect the amplifiers to shut down because of not receiving commands?

- Will the PMAC card pass MACRO commands through that were generated by another device on the ring?

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The manual is referring to the actions taken locally (i.e. axes, I/O, communication).


A PMAC ring controller watchdog will generate a ring break, and MACRO ring error(s). Typically, the MACRO stations' intelligence shuts down everything "locally".


- No, the PMAC cannot anticipate a watchdog to send disable commands.

- PMAC will halt communication locally, and over MACRO. Nothing goes out.

- No, PMAC will cease communication completely in a watchdog state.

- Yes, the amplifiers should kill if there is a PMAC watchdog (due to ring break and or MACRO ring error(s))

- This is an unusual question because the PMAC (ring controller) is usually handling the data transfer over MACRO. But no, the PMAC will not pass commands or data. The MACRO link LED goes red indicating a ring break.

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Thanks Richard. Does the last command value (and command/status word) transferred prior to watchdog remain in the node, but rely on the heartbeat settings of the node (Mi8,Mi9,Mi10) to shut down the motor?


The last question about passing data through the PMAC would be useful if we had a redundant PMAC on the ring.

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If you want to put it this way, yes. But the hardware link break also generates an error faster than the software ring check. So at worst, the shutdown is a phase cycle behind. Any subsequent commands are ignored and dropped until the ring is re-established and faults are cleared on both the ring controller and station.


Yes, I figured that would be one reason to ask about another master on the ring.

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