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Author Topic: Mamiya/Phase One Camera to back communication protocol  (Read 477 times)

Alexey.Danilchenko

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Mamiya/Phase One Camera to back communication protocol
« on: January 24, 2018, 05:20:43 AM »

In the course if me adapting old Kodak ProBack 645M to work with Mamiya/Phase One DF/DF+ bodies I have reverse engineered the camera to back communications protocol for Mamiya/Phase One cameras (from Mamiya 645 AFD up to DF/DF+). This is now fully documented here and released for free to anyone interested. This may prove useful to anyone designing their own back (DIY or else) and vice versa designing their own camera interfacing with the backs supporting Mamiya/Phase One connection.
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Graham Welland

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Re: Mamiya/Phase One Camera to back communication protocol
« Reply #1 on: January 26, 2018, 03:24:38 AM »

Very interesting read. Perhaps you can get to the bottom of why the protocol timing would often result in back/db lockups. I shot the AFD/AFD II/DF/DF+ and 645M, Aptus, P25+, P40+ and IQ160/IQ260 and all of them locked up at some point. XF and IQ3 series seem to have fixed almost all issues.

As a systems developer of communications protocols and definitive state machines that avoid/recover from such messaging errors I've always been of the opinion that the protocol or implementation was flawed based on timing assumptions vs robust messaging protocol. (My background was designing and implementing real time stock price & trading systems - things you can never lock up!)
« Last Edit: January 26, 2018, 03:34:47 AM by Graham Welland »
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Graham

Alexey.Danilchenko

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Re: Mamiya/Phase One Camera to back communication protocol
« Reply #2 on: January 26, 2018, 03:52:02 AM »

Very interesting read. Perhaps you can get to the bottom of why the protocol timing would often result in back/db lockups. I shot the AFD/AFD II/DF/DF+ and 645M, Aptus, P25+, P40+ and IQ160/IQ260 and all of them locked up at some point. XF and IQ3 series seem to have fixed almost all issues.
If 645M means ProBack - then I have not had lock on AFD and AFD II no matter how hard I tried. That of course means non-defective back with no problems in hardware. From my experiments those older bodies simply go to No DB mode without locking up the way DF/DF+ does. I had AFD/AFDII locked down in a different ways when camera body stopped responding to any button presses and to the camera. But that was all the time due to battery.

As a systems developer of communications protocols and definitive state machines that avoid/recover from such messaging errors I've always been of the opinion that the protocol or implementation was flawed based on timing assumptions vs robust messaging protocol. (My background was designing and implementing real time stock price & trading systems - things you can never lock up!)
The impression I have that on DF/DF+ bodies it was done rather deliberately to force people to upgrade to the newer faster backs with ability to handle fast communications and respond in time. I see absolutely no reason for not recovering when the back misses the message and perhaps reverting the sequence and going to normal mode would have been far safer. DF/DF+ instead flap the mirror and hang up (the body then always sends just one message with no data and getting it out of that state is only possible by hard reboot by battery replacement - well at least I have not found a message sequence from the back to restore it to normal).

I think reading various forums this "design decision" came to bite Phase One as well since there were problems with some Pxx back on some DF/DF+ firmware versions (I suppose due to perhaps some timing issues). I have updated Kodak ProBack firmware to cater for most of those but it will only work reliably in long shutter latency mode where timings are delayed by the body.

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Graham Welland

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Re: Mamiya/Phase One Camera to back communication protocol
« Reply #3 on: January 26, 2018, 04:26:35 AM »

Your description of the recovery process matches EXACTLY what I had to do for many years. In fact you could hear the body go KLUNK vs click when it happened. As you explained, battery out reset required to fix every time.

Regarding Kodak - I had two DCS 645M bodies. I always wanted the 645 Pro because of it's tilting display ...
« Last Edit: January 26, 2018, 04:30:32 AM by Graham Welland »
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Graham

Graham Welland

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Re: Mamiya/Phase One Camera to back communication protocol
« Reply #4 on: January 26, 2018, 04:28:20 AM »

Btw relying on timing vs responsive protocols that either ACK or retry is just poor protocol design.
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Graham

Alexey.Danilchenko

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Re: Mamiya/Phase One Camera to back communication protocol
« Reply #5 on: January 26, 2018, 07:00:58 AM »

Btw relying on timing vs responsive protocols that either ACK or retry is just poor protocol design.

I totally agree Graham - but in this case unfortunately we are where we are. So I adjusted 645M firmware to deal with it.
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