Comments on: Optoisolator cards for Mesa 5i20 servocard http://www.anderswallin.net/2006/08/optoisolator-cards-for-mesa-5i20-servocard/ Wed, 08 Feb 2012 22:20:27 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Administrator http://www.anderswallin.net/2006/08/optoisolator-cards-for-mesa-5i20-servocard/#comment-192 Administrator Sat, 27 Oct 2007 06:33:14 +0000 http://www.anderswallin.net/2006/08/optoisolator-cards-for-mesa-5i20-servocard/#comment-192 Hi Daniel, Optoisolation is used to protect the computer and the m5i20 from bad things that might happen at the servodrive/motor end. If for example something goes wrong and the full motor voltage (say 100V) is connected to the logic gates on the m5i20 then it is likely that the card will be damaged and maybe the computer too. With an isolation stage between the card and the drives it is likely that only the optoisolators will be damaged - card/computer would be saved. Anders Hi Daniel,

Optoisolation is used to protect the computer and the m5i20 from bad things that might happen at the servodrive/motor end.
If for example something goes wrong and the full motor voltage (say 100V) is connected to the logic gates on the m5i20 then it is likely that the card will be damaged and maybe the computer too.
With an isolation stage between the card and the drives it is likely that only the optoisolators will be damaged - card/computer would be saved.

Anders

]]> By: Daniel http://www.anderswallin.net/2006/08/optoisolator-cards-for-mesa-5i20-servocard/#comment-191 Daniel Wed, 24 Oct 2007 07:05:00 +0000 http://www.anderswallin.net/2006/08/optoisolator-cards-for-mesa-5i20-servocard/#comment-191 Hallo, I am currently trying to run a servo system using m5i20 and 7i33 card from Mesa. I am wondering what is the use of the optoisolator card and why do you need to use the optoisolator card as I am reading about your post? Thanks. Daniel Hallo,

I am currently trying to run a servo system using m5i20 and 7i33 card from Mesa. I am wondering what is the use of the optoisolator card and why do you need to use the optoisolator card as I am reading about your post?

Thanks.
Daniel

]]> By: Administrator http://www.anderswallin.net/2006/08/optoisolator-cards-for-mesa-5i20-servocard/#comment-190 Administrator Fri, 15 Dec 2006 08:39:21 +0000 http://www.anderswallin.net/2006/08/optoisolator-cards-for-mesa-5i20-servocard/#comment-190 The m5i20 has three 50-pin connectors. In the Hostmot-4 FPGA configuration (the one that currently comes with EMC2) these are used as follows: One for motion control, and two for general purpose I/O. Look in the manual at: http://www.linuxcnc.org/docs/2.1/ The pinout and the number of inputs and outputs on the 7i37 is well suited for the general purpose I/O connetor (16 inputs, 8 outputs). It would be quite hard to make a custom cable or connector block or something that would map the pins from the 50-pin motion control connector to a 7i37 correctly.... and as you say it requires 12 inputs and 12 outputs, not 16/8. I made my optoisolator card for the motioncintrol pins a while ago, but now I'm finding that most servodrives have optoisolated inputs anyway. And the encoder signals probably do not need optoisolation since they run off a separate +5V source. So to conclude it might not be neccessary to optoisolate the motioncontrol part of the m5i20 card since most servodrives have optoisolation anyway. If you are considering a servo to go (or vital) as an alternative you should note that the m5i20 outputs PWM for motor control, notanalog +/- 10 V as the stg/vital. (Mesa makes a board for converting the dir+pwm signals to +/- 10 V) Anders The m5i20 has three 50-pin connectors. In the Hostmot-4 FPGA configuration (the one that currently comes with EMC2) these are used as follows: One for motion control, and two for general purpose I/O. Look in the manual at:
http://www.linuxcnc.org/docs/2.1/

The pinout and the number of inputs and outputs on the 7i37 is well suited for the general purpose I/O connetor (16 inputs, 8 outputs).

It would be quite hard to make a custom cable or connector block or something that would map the pins from the 50-pin motion control connector to a 7i37 correctly.... and as you say it requires 12 inputs and 12 outputs, not 16/8.

I made my optoisolator card for the motioncintrol pins a while ago, but now I'm finding that most servodrives have optoisolated inputs anyway. And the encoder signals probably do not need optoisolation since they run off a separate +5V source. So to conclude it might not be neccessary to optoisolate the motioncontrol part of the m5i20 card since most servodrives have optoisolation anyway.

If you are considering a servo to go (or vital) as an alternative you should note that the m5i20 outputs PWM for motor control, notanalog +/- 10 V as the stg/vital. (Mesa makes a board for converting the dir+pwm signals to +/- 10 V)
Anders

]]> By: Tom M. http://www.anderswallin.net/2006/08/optoisolator-cards-for-mesa-5i20-servocard/#comment-189 Tom M. Fri, 15 Dec 2006 08:25:41 +0000 http://www.anderswallin.net/2006/08/optoisolator-cards-for-mesa-5i20-servocard/#comment-189 I'm looking at using the 5i20 with EMC. Perhaps you can say why one wouldn't want to use three Mesa 7i37 boards: one for the general purpose I/O, and two for the motor control? Obviously, this wastes some inputs, as the motor control requires 12 inputs & 12 outputs, but each 7i37 only has 8 outputs and 16 inputs, but using a 5i20 and buying three of the 7i37 is still a lot cheaper than using a Servo-to-go board. Thanks! I'm looking at using the 5i20 with EMC. Perhaps you can say why one wouldn't want to use three Mesa 7i37 boards: one for the general purpose I/O, and two for the motor control? Obviously, this wastes some inputs, as the motor control requires 12 inputs & 12 outputs, but each 7i37 only has 8 outputs and 16 inputs, but using a 5i20 and buying three of the 7i37 is still a lot cheaper than using a Servo-to-go board.

Thanks!

]]> By: Administrator http://www.anderswallin.net/2006/08/optoisolator-cards-for-mesa-5i20-servocard/#comment-188 Administrator Fri, 15 Dec 2006 06:36:40 +0000 http://www.anderswallin.net/2006/08/optoisolator-cards-for-mesa-5i20-servocard/#comment-188 Your following error is a good sign, it means that the encoders are probably working OK. you should check all components in the chain one by one. does the motor spin, both ways, when you connect a voltage over the terminals (and reverse the voltage). does the m5i20 output the correct signals (DIR, PWM, Amp enable) ? Look at HAL pins with HALscope. Does the motioncontroller output the correct singals (motion-cmd should be the same as the axis position shown on screen). then connect the PID loop and look with HALscope at the output. Anders Your following error is a good sign, it means that the encoders are probably working OK.

you should check all components in the chain one by one.

does the motor spin, both ways, when you connect a voltage over the terminals (and reverse the voltage).

does the m5i20 output the correct signals (DIR, PWM, Amp enable) ?

Look at HAL pins with HALscope. Does the motioncontroller output the correct singals (motion-cmd should be the same as the axis position shown on screen).

then connect the PID loop and look with HALscope at the output.

Anders

]]> By: Ali Sayed http://www.anderswallin.net/2006/08/optoisolator-cards-for-mesa-5i20-servocard/#comment-187 Ali Sayed Fri, 15 Dec 2006 03:17:55 +0000 http://www.anderswallin.net/2006/08/optoisolator-cards-for-mesa-5i20-servocard/#comment-187 Hello - I was wondering if you can help out with the Mesa 5i20 configuration. I am using a 7i30 H-Bridge to drive DC Brush motors, So far I have only been able to get the encoders to work, and something seems to not be right with the PID loop, I have no power to the motors. Jogging causes following erros without any response from the motors. Thanks -ali Hello -

I was wondering if you can help out with the Mesa 5i20 configuration. I am using a 7i30 H-Bridge to drive DC Brush motors, So far I have only been able to get the encoders to work, and something seems to not be right with the PID loop, I have no power to the motors. Jogging causes following erros without any response from the motors.

Thanks

-ali

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