Unit values and speed jumpers on prt control box

[jseiler]

I got a prt box and hooked it up to some motors. I figured out the unit values I needed by trying various ones until they worked.

x and y : 4000
z: 4000

This makes all the motors turn 10 times for every 1" commanded.

The speed jumpers are a matrix labelled a, b, c and 1, 2, 3, 4, 1', 2', 3' and 4'.

the x1, x2 and y are all jumpered the same.

one jumper between columns b and c on the "2" setting. no other jumpers.

the z is different. 2 jumpers.
1 between b and c columns on the "2" setting row
1 between b and c columns on the "1" setting.

I presume this is controlling the microstepping of the board. What does it mean? I can't find any documentation anywhere on how to change these jumpers.

John

[jseiler]

Ok, I took apart the box and I have IMS drivers. I disassembled the heat sink assembly and pulled the driver, IM481. I didn't rigorously schematic out the board, but a quick look makes it appear as if they are just bringing various line high to set the "resolution" aka microstepping. It looks like x1, x2 and y are set to 1/4 stepping and z is set to 1/16 stepping. My question is....why is the z unit value the same as x1, x2, and y? Is there some hidden factor of 4?

John

[jseiler]

I experimented by clipping the z lead on the "1" position. this made all the axes the same on the speed jumper settings...just 1 jumper on the "2" position.

This required that I change the unit value on z axis to 8000 to maintain 10 revolutions/inch. Curiously, when I set the speed to .1ips, it took each axis the exact same amount of time to transition the 10 revolutions of the motor. About 13 seconds (including the motor startup lag).

Is this set to 1/4 or 1/8 stepping?
Why is the z unit value different?
How do I get to 1/2 or other stepping modes?

(I'm using the latest version of the windows software and updated the firmware on the box to match).

This is driving me nuts.
John

[jseiler]

With Ted's help, I finally got it figured out.

The jumpers pull the microstepping lines LOW (not high), the driver, left open, will pull high (pulled high internally to driver).

The confusing part is that some of the jumper spots are tied low with traces. If you really wanted to change those, you'd have to razor blade those traces. The other confusing bit is that the jumpers marked ' are parallel to the ones marked without the "'" (i.e. 1' is parallel to 1, you can jumper at either spot).

1 2 3 4

L L L L 1/2 stepping
H L L L 1/4 stepping
L H L L 1/8 stepping
H H L L 1/16 stepping
L L H L 1/32 stepping

L L L H full stepping

On my box, on the x1, x2, and y, lines 4, 3 and 1' were set low with traces (factory setting of 1/8). Someone had added a jumper to the 2 position, setting up for 1/2 stepping.

The z had factory traces on 4, 3 setting up 1/16 stepping. Changes were made to add jumpers to 2 and 1, setting up 1/2 stepping.

This is what made the unit values the same even though the jumpers were different. When I clipped the "1" jumper on the z, I had to change the unit value to 2x that of the x1, x2, and y settings. This was because I had changed the speed setting to 1/4 stepping.

Thanks to Ted for helping me see the light. Gotta love shopbot tech suppport.


I think I'm going to use this box to upgrade my pr32 with old pr 1/2 step controls and 28V power supply.

On another note, can anyone verify the step rate on the PRT box with allegro drivers? Ted says the step rate on the PRT box with IMS drivers is about 4K.

John