Issues with Roboteq AX1500 control board in dual-analog input mode.

<P class=MsoNormal style="MARGIN: 0px"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Hello, </SPAN>
<P class=MsoNormal style="MARGIN: 0px"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">I’ve recently purchased a couple of AX1500 boards and am looking to use them to control a dual-channel analog positioning system.<SPAN style="mso-spacerun: yes"> </SPAN>I’m going to be using a 0-5v input to control the position (on pins 11 and 10 of the d-type) and providing a 0-5v feedback signal to the analog inputs 3 and 4 (on pins 12 and 8).</SPAN>
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<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Firstly, I’ve tried the first board and have not been able to connect to the board with the Roborun software via the RS232 control cable.<SPAN style="mso-spacerun: yes"> </SPAN>When the board is connected the power light is lit but the software connection is unable to establish contract with the board (and the status light does not light up).<SPAN style="mso-spacerun: yes"> </SPAN>I’ve tried this initial setup with a separate board and have been able to connect to the system immediately, with the Roborun software detecting the controller settings and allowing comms with the board.<SPAN style="mso-spacerun: yes"> </SPAN>I’ve looked through the forum and the manual and have been unable to find anything to help solve this issue.<SPAN style="mso-spacerun: yes"> </SPAN>Is this likely to be a faulty board? Any ideas on this would be gratefully accepted.</SPAN>
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<P class=MsoNormal style="MARGIN: 0px"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Secondly- I’ve been able to set-up a second board using the Roborun software and have set the system to run in dual-analog positioning mode.<SPAN style="mso-spacerun: yes"> </SPAN>I’m initially, using a pair of 5k variable pots to provide the feedback signal (not the 2k recommended but these are the ones I’ve got in at short notice- is this likely to cause positioning errors and non-linearity or will it do something more subtle?). </SPAN>
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<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">I’ve now set the system to move to the voltage demand and have noticed a few quirks with the system.<SPAN style="mso-spacerun: yes"> </SPAN>I know the system requires an initial 2.5v signal to be applied to the input line before the board is initialized and I seen this when operating the system.<SPAN style="mso-spacerun: yes"> </SPAN>However, when I adjust my input demand I see that the system responds to an input demand of approximately 3-7v rather than the 0-5v signal I was expecting (i.e. I see the movement range being 3v to 7v rather than seeing the movement begin after the 2.5v threshold is reached and then seeing movment over the range 0-5v).<SPAN style="mso-spacerun: yes"> </SPAN>Is this likely to be a function of my pot selection or is there something I’m missing here.</SPAN>
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<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Many thanks in advance for your help.</SPAN>
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<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Pc</SPAN>

Your first unit appears to be bad. Upon power up, the status led should be flashing even if nothing is connected to it. Please use our contact form at <A href="dev.roboteq.com/dev1/contactus.html" target=_blank>www.roboteq.com/contactus.html to arrange for a return.

Using the latest revision of the firmware and PC utility it is normally possible to disable the 2.5V at startup requirement.

5K pot is not a problem. A higher value pot affects the linearity of the voltage created across the pot's range but if both pots are identical, they will compensate for each other.

3-7V doesnt make sense. The board's A/D converter cannot read voltages above 5V.

In your case, the best is to first try to make the controller work using the PC utility. This way you can see what value is reported by the pot feedback and verify that the motor move in to reach the value that you set with the slider. When you are happy that your system responds well, you can set it to analog mode.

Beware however that when in RS232 mode, pot feedback go to Analog inputs 1 and 2. In RS232 mode, command goes to Ana 1 and 2, feedback on 2 and 3.

You need to wire the controller for the analog mode. When on Roborun, make sure that you select the Analog mode and save to controllers. After you are done with Roborun, make sure you reset the controller for it to use the pot for command instead of the PC sliders.

<P style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Verdana"><FONT face="arial, helvetica, sans-serif">Firstly, thanks for the prompt reply to my inquiries.</FONT></SPAN>
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<P style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 12pt"><FONT face="arial, helvetica, sans-serif"><FONT size=2>I was also surprised by the seemingly high input demand voltage required to see system movement.<SPAN style="mso-spacerun: yes"> </SPAN>I’ve checked on the input lines and it seems to be a ‘real’ signal and have tried altering the PID settings to see if it’s a demand-power issue.<SPAN style="mso-spacerun: yes"> </SPAN>This demand signal was provided from a PSU but I don’t think that this should cause an issue as its just supplying a line voltage. (As an aside- are there any test pins on the board that will allow me to look at the internal voltage/signal levels?) <SPAN style="mso-spacerun: yes"> </SPAN></FONT></FONT></SPAN>
<P style="MARGIN: 0cm 0cm 0pt"><FONT face="arial, helvetica, sans-serif"><FONT size=2><SPAN style="FONT-SIZE: 12pt"><FONT size=2><SPAN style="mso-spacerun: yes"> </SPAN>I’ve emailed you a sketch of the set-up I’ve used below and cant seems to see where it might go awry (would post it but its not letting me).<SPAN style="mso-spacerun: yes"> </SPAN>I’ve sketched the pins I’ve used for the just the single channel I’ve connected to test.<SPAN style="mso-spacerun: yes"> </SPAN>I’ve checked feedback pot polarity is correct and the system seems to move in the way I expect ( i.e. moving and then stopping at required position) except for the high voltage required on the input.</FONT><SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN style="FONT-FAMILY: Arial">I’ll be looking to make up a cable to look at the RS232 control soon (I’m currently alternating between controller setup using the 15-way d-type and a custom-made cable to link to the motion system.</SPAN></FONT></FONT>
<P style="MARGIN: 0cm 0cm 0pt"><FONT face="arial, helvetica, sans-serif" size=2><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: Arial"> </SPAN></FONT>
<P style="MARGIN: 0cm 0cm 0pt"><FONT face="arial, helvetica, sans-serif"><FONT size=1><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: Arial"><FONT size=2>Finally, I’m interested by the option of disabling the 2.5v start-up voltage requirement.<SPAN style="mso-spacerun: yes"> </SPAN>Am I correct in thinking that this will be done through the Roborun software?<SPAN style="mso-spacerun: yes"> </SPAN>If I download the latest firmware rev</FONT> <FONT size=2>(</FONT></SPAN><FONT color=#222222><SPAN style="FONT-SIZE: 8.5pt; COLOR: #222222; FONT-FAMILY: Arial"><A href="dev.roboteq.com/dev1/register.html" target=_blank target=_blank>roboup19b-060107) is this option then allowed in the Roborun software?
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<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><FONT face="arial, helvetica, sans-serif">Many thanks for the help.</FONT></SPAN>
<P class=MsoNormal style="MARGIN: 0px"><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><FONT face="arial, helvetica, sans-serif">Pc</FONT></SPAN>
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The best way to see what the controller "measures" on the analog inputs is to use the PC utility. In the run tab, you will see a box for each Ana inputs. Value is displayed as a number from -127 (at 0V) to +127 (at 5V), 0 is 2.5V.

It appears that Roborun does not alway show the option to disable the startup safety. You may disable it manually by clicking on the Console tab, sending ^05 01 and sending ^FF