Signal measuring advice - Page 1
Forum section: electronics / beginners

author: gabi68
author_rank: Newbie
timestamp: December 12, 2021, 09:22:47 am
content: Hi to all,Super newbie here.Problem: I have a fiber laser which has 2 stepper motors (one for the Z axis and one for the rotary axis A) with the appropriate drivers (DM542) and for some reason one of them stop working (the Z axis). The whole thing is controlled by a board (DLC2-M4-2D) made it by BJJCZ in China (they dominate the market with their products). The DLC2 board has 4 ports - Z, A, X, Y and can be configured to A - rotary, Z - up and down, X - x axis, Y - y axis and combination of those i.e XY, XZ, ZA, ...The laser is working like a CNC with limit and home switches. At start up it needs to do a homing sequence to know where it is. When I try to do that the software reports "Axis is homing", but in reality noting is moving. If I power everything down and change the port to X driver still nothing, change it to Y or A everything is moving, but is very hard to reconfigure Y or A to use like a Z axis (no homing on this and other things are not configurable).Talking with Chinese people is not easy and the time difference is a big factor (UK to China), but they are keep saying the connection is the problem (loose wire from the DLC board to the drivers). I need to find a way to convince them the board is shot and send a replacement (the machine is still under warranty).Where I need help: I have an Hantek 6022BE and I need guidance on how to measure if the signal is coming out from the DLC board or not. The DLC board is powered form a Meanwell 12V power supply and I have 12V at the board connectors. I also have 5V at the DB9 connectors going to the stepper drive (measured with a Fluke multimeter).How can I use safely the Hantek to measure the signal (if is there or not)?I will attach some pictures and a DB9 connector pin connection to have a better understanding.Thank you in advanceGabi

author: gabi68
author_rank: Newbie
timestamp: December 12, 2021, 04:14:33 pm
content: Any advice,please?

author: bob91343
author_rank: Super Contributor
timestamp: December 12, 2021, 06:28:02 pm
content: No problem. First connect the Hantek ground to the system ground and then the input to any of the terminals you want to measure.

author: gabi68
author_rank: Newbie
timestamp: December 12, 2021, 08:18:38 pm
content: Being in the UK we have a 3 prongs on the wall plug which means there is ground. The machine has a star ground thru a screw on the back with a connector and a wire which needs to be grounded, but I was told I don't need to use it.It will be fine to use the star ground with the Hantek ground or should I find another place?Sorry for newbie question's.Thank youGabi

author: ledtester
author_rank: Super Contributor
timestamp: December 12, 2021, 09:17:59 pm
content: The Hantek is a USB scope. What computer are you going to use with it? I think it would be safest to connect it to a laptop running on batteries (i.e. with the AC charger NOT plugged in).You also want to spend some time to understand the grounding situation with the Meanwell. It might be better to power the driver board from a floating power supply (like a floating bench supply).Here is another discussion about probing a stepper driver with an oscilloscope:https://www.eevblog.com/forum/beginners/how-to-hook-up-an-oscilloscope-to-a-stepper-motor-driver/

author: gabi68
author_rank: Newbie
timestamp: December 14, 2021, 09:42:43 am
content: Quote from: bob91343 on December 12, 2021, 06:28:02 pmI tried that and I can see some activity on the screen, but... If I try to move the stepper nothing is change on the screen. My understanding is a stepper motor needs pul and dir to move (correct me if I am wrong - newbie here).With that assumption in mind should I hook up the second probe on the scope with 1 probe the dir+ and with 2 probe the pul+ and both probes connected to the system ground and everything running from a laptop without charging?Thank you

author: gabi68
author_rank: Newbie
timestamp: December 14, 2021, 09:40:06 pm
content: I am thinking right?

author: bob91343
author_rank: Super Contributor
timestamp: December 15, 2021, 12:33:48 am
content: I don't understand your terminology.

author: gabi68
author_rank: Newbie
timestamp: December 15, 2021, 10:35:30 pm
content: That board needs to move a stepper motor. The board has 4 ports: Z, A,X, Y. The Z and Y are not working, but in order to be sure the manufacturer ask all kind of questions and they say the board is fine. I need to prove they are wrong and for this I need to measure the voltage coming from the bad ports.This is all about.I hook up the Hantek with the ground on the system ground and the probe to Dir + (which is the direction). As I said I see some activity on the screen, but I dont understand what I am seeing.I would like to see a sinusoid (or not) when I try to move the motor, but in order to see that I need dir+ and pul+ (meaning direction and pulse). This was my question: hook up the Hantek with 2 probes - both grounds tied to system ground and 1 probe to dir+ and the another one to pul+.What do you think?

author: gabi68
author_rank: Newbie
timestamp: December 16, 2021, 08:07:31 pm
content: Any thoughts?