Shopbot PRSalpha router converted to Kflop KmotionCNC with rs-485 (shopbot2kflop)


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Thread: Shopbot PRSalpha router converted to Kflop KmotionCNC with rs-485 (shopbot2kflop)

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    Default Shopbot PRSalpha router converted to Kflop KmotionCNC with rs-485 (shopbot2kflop)

    Firstly, I'd like to thank everyone who helped me sort a few issues and answer questions along the way. The Shopbot PRSalpha Buddy (2'x4') router has been completed for a few weeks are has been working exceptionally well. I happened into Kflop after reading about a similar conversion by kirilian of his Shopbot BT32 to Mach3: http://www.cnczone.com/forums/commer...-software.html Rather than Mach 3 I opted to use KmotionCNC and I couldn't be happier.

    I decided to post a few details here because I figured it may help a few others. Particularly with the direct TTL to RS-485. I was pretty apprehensive about converting a running machine but over the past year of issues with the Shopbot software I decided to make the switch.

    Because I didn't want to physically modify the original machine I designed an adapter board to convert using the same connectors as the original SB motion controller, that way I could convert back if I ever needed to. One of my concerns was the VFD control via RS-485 using modbus. The SB software would lockup if I left the RPM window open which I wasn't sure if it was a PC issue or a SB issue. So I decided I'd have the Kflop handle the modbus directly. I found a very in-expensive TTL_RS485 module on Amazon that would handle 3.3V LVTTL. Once everything was proto-typed and working, I designed a PCB in Eagle and sent the design to a pcb house. I include an RJ-11 socket to plug in to the original VFD cable and a socket for the TTL_RS485 module. Turned out very professional.

    When I was researching the RS-485 stuff I found the information to be a bit thin. It appeared most people are using modpoll on the PC or were using Kanalog with an adapter. I wanted to handle it directly. So far this module has worked brilliantly. It draws very little allowing me to power it directly off the Kflop.

    In addition to plugging in the adapter, I did put 14N007 flyback diodes on the contractor coils and installed a z-axis proximity switch which simplified my homing routine. I ordered the proximity switch Shopbot for $87.50 – part number 14601.

    Here's the TTL_RS485 module details:
    UART TTL to RS485 Two-way Converter Module [TTL-RS485-Module] - US $2.80 : HAOYU Electronics : Make Engineers Job Easier

    Shopbot PRSalpha router converted to Kflop KmotionCNC with rs-485 (shopbot2kflop)-ttl_rs485-png

    Here's the board in Eagle. First Eagle project ever. Awesome software.
    Shopbot PRSalpha router converted to Kflop KmotionCNC with rs-485 (shopbot2kflop)-shopbot2kflop2-png

    The board without the TTL_RS485 module.
    Shopbot PRSalpha router converted to Kflop KmotionCNC with rs-485 (shopbot2kflop)-img_2567-1-jpg

    Completed board ready to install.
    Shopbot PRSalpha router converted to Kflop KmotionCNC with rs-485 (shopbot2kflop)-img_2568-1-jpg

    Installed with the Kflop in the back ground.
    Shopbot PRSalpha router converted to Kflop KmotionCNC with rs-485 (shopbot2kflop)-img_2569-1-jpg

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    Default Re: Shopbot PRSalpha router converted to Kflop KmotionCNC with rs-485 (shopbot2kflop)

    Hi forhire,

    That looks really cool. Feel free to advertise those for sale here in our forum if you wish.

    Regards

    Regards
    TK http://dynomotion.com


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    Default Re: Shopbot PRSalpha router converted to Kflop KmotionCNC with rs-485 (shopbot2kflop)

    Quote Originally Posted by TomKerekes View Post
    That looks really cool. Feel free to advertise those for sale here in our forum if you wish.
    Thanks Tom. I ended up with four extra boards. Unfortunately I really doubt it will generate much interest, most of the Shopbot guys are fiercely loyal to their two-letter mnemonics language. This machine is used in a teaching environment and the OpenSBP was just too different from the other real g-code controlled machines. The shop has a Centroid based cnc knee mill and a Fanuc 15MA based VMC. Cross training across the environments was a huge pain this year. The router makes a perfectly forgiving environment to train. Shopbot claims it supports g-code but the interpreter is very limited. The students start with some basic hand coding exercises like a name plate and a cribbage board. This gets them familiar with both linear moves, arcs, and drilling. We then finish out with basic cam by doing an engraving and a 2.5d/3d part. The first snag we hit was the fact the Shopbot didn't support any canned drilling operations. Obviously, the cam package posts very clean and reliable code... but being able to a least read g-code and perform basic MDI instructions is important... especially when running the machine with the old Fanuc. So far I couldn't be happier with the conversion. The students really like it. I expect great things come the fall.



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    Default Re: Shopbot PRSalpha router converted to Kflop KmotionCNC with rs-485 (shopbot2kflop)

    Another user wanted to see "working" modbus code. This was a quick hack of the included sample. It's very rough but for the most part it works ok. A rework has been on my to-do list for a while. My brother Jason and I did most of the edits one evening and haven't looked at it since.

    Attached Files Attached Files


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Shopbot PRSalpha router converted to Kflop KmotionCNC with rs-485 (shopbot2kflop)

Shopbot PRSalpha router converted to Kflop KmotionCNC with rs-485 (shopbot2kflop)