[andrewboerder]

Hi so i have a fanuc p-155 robot that i want to retrofit but im having trouble figuring out the encoder signals on the robot pin outs they are listed as 1D, 1*D, 1RQ, and 1*RQ and then of course 5 volt and 0 volts....what would be the difference between this type of encoder and say a pulse coder with signals A,B,Z

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[PCW_MESA]

Hi so i have a fanuc p-155 robot that i want to retrofit but im having trouble figuring out the encoder signals on the robot pin outs they are listed as 1D, 1*D, 1RQ, and 1*RQ and then of course 5 volt and 0 volts....what would be the difference between this type of encoder and say a pulse coder with signals A,B,Z

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That is a serial absolute encoder with differential (RS422) Request and Data signals

A request pulse is sent on the RQ lines and position,status, and error checking data is returned on the D lines (76 bits of data at 1.024 MBits/sec)
That model is absolute with battery backup ( important so you always know the robot joint positions at start-up )
and has 65536 counts per turn resolution and a 16 bit turn counter, in addition it has a 10 bit commutation track that's not dependent on the battery backup.

[andrewboerder]

Fantastic thanks, do you have a data sheet or do you just know this? Are the two request and data signals the same or are they out of phase with one another?

That is a serial absolute encoder with differential (RS422) Request and Data signals

A request pulse is sent on the RQ lines and position,status, and error checking data is returned on the D lines (76 bits of data at 1.024 MBits/sec)
That model is absolute with battery backup ( important so you always know the robot joint positions at start-up )
and has 65536 counts per turn resolution and a 16 bit turn counter, in addition it has a 10 bit commutation track that's not dependent on the battery backup.

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[PCW_MESA]

Fantastic thanks, do you have a data sheet or do you just know this? Are the two request and data signals the same or are they out of phase with one another?

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I reverse engineered the protocol to add it to our FPGA motion interface firmware suite
This firmware is open source if you are curious.

The request is simply a pulse ( the 2 request and data lines are 180 degrees out of phase= standard RS-422 differential signaling )
the return data is asynchronous (no clock) basically received by a 76 bit UART at 1,024 KBaud (newer one use higher baud rates)

[Al_The_Man]

It is customary in commercial robots to use absolute encoders, no zeroing needed at power up, as it is with Quadrature version.
Al.

[andrewboerder]

I am quite interested where do i find this firmware....im looking to use stmbl open source drives with mesa interface.....the developers have a,b,z fanuc encoders compatible but i have yet to find out whether or not differential absolute encoders are supported. Im going to seek to understand the protocol better before i ask.

I reverse engineered the protocol to add it to our FPGA motion interface firmware suite
This firmware is open source if you are curious.

The request is simply a pulse ( the 2 request and data lines are 180 degrees out of phase= standard RS-422 differential signaling )
the return data is asynchronous (no clock) basically received by a 76 bit UART at 1,024 KBaud (newer one use higher baud rates)

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[PCW_MESA]

Pretty sure STMBL already supports Fanuc serial pulsecoders but you may need to ask Rene what the current status is
The firmware and source is included in the zip support file for any Mesa FPGA card

[andrewboerder]

Ok kewl....so are fanuc A,B,Z encoders just regular quadrature architecture? Thank you all very much for your correspondence

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[Al_The_Man]

Fanuc ABZ encoders have the standard differential RS485 A /A, B /B, Z /Z signals.
Al.

[andrewboerder]

Obviously i have much to learn about about encoder signal architecture.....thanks yall for pointing me in the right direction.

Fanuc ABZ encoders have the standard differential RS485 A /A, B /B, Z /Z signals.
Al.

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