[dinkyguitar]

Thanks adam_m,

The motors from Keling, did you have to wire the resistor and crimp the DB9 connectors?

dinkyguitar,

[adam_m]

I'm just getting ready to start my build so I haven't even un-boxed them yet... I did crack the lid to make sure it was there ;-)

My understanding is that the G540 resistors needed are built into the cables from CNC router Parts which is why I bought them from them (CNC Motor Cable | CNCRouterParts)

The motors themselves will need to have the connectors added, no big deal, in my opinion. However I wanted to buy a good quality communication cable which is what I think CNC Router Parts is selling, I've not been disappointed with anything from them yet. I think you will get the same response from those on the forum who has used them in the past, good quality products.

Can someone chime in who has purchased the same cables from CNC Router Parts to let me know if I am incorrect in my understanding of the built in resistor.

Adam,

[Lee DeRaud]

Can someone chime in who has purchased the same cables from CNC Router Parts to let me know if I am incorrect in my understanding of the built in resistor.

AFAIK, the resistors are in the DB9 connector on the motor pigtail, not the cables. Easiest way to tell is measure the resistance between pins 1 and 5 at either end of the cable.

That said, I had a problem with motor overheating on the Z-axis (the longest cable). Ahren of CNCRP said it was due to noise in the cable interfering with the G540's ability to read the resistor at the other end. He supplied a set of short stub cables to put at the G540 end that also had the resistors wired in. So it's possible they're implementing it differently in products shipped now.

[adam_m]

CNCRP has the following in the description:

"These cables also feature an overmolded 3.5 kOhm resistor between pins 1 and 5 on the drive (male) connector side, and a drain wire from the shielding to pin 2 of the cable. This sets the current on a G540 to 3.5A/phase to support our motors and popular motors from other vendors, and minimizes electrical noise both to the drive and other sensitive electronics."

A doubling the resistance wouldn't be good...

[Lee DeRaud]

CNCRP has the following in the description:



A doubling the resistance wouldn't be good...

It wouldn't double, even if you matched that cable with an old resistor-equipped motor: if the resistor is at the drive end of the cable, there's no need to connect the pin 1/5 wires to the other end, so a resistor at the motor end doesn't do anything.

This implementation only has one potential problem that I can see: the cables are now motor-current-specific. Not an issue if you're buying a kit, but something to keep in mind if you're doing a mix/match with multiple vendors.

[dinkyguitar]

Just an FYI, I was reading the G540 manual and it says that if your using 3.5a motors you don't need a resistor....

"If your motors are rated below 3.5A you must use a current set resistor across PIN 1 and PIN 5. The resistor is calculated by taking the current in amps and multiplying by 1000. If your motor is rated at 2.8A per phase you will have to use a 2.8K 5% 1/4W resistor. If your motor is rated at 3.5A or above you can safely not use a current set resistor; however, your G540 will not go into current standby mode which will result in increased motor heating."

But what does this mean? And what resistor would you use on a 3.5a motor??

"however, your G540 will not go into current standby mode which will result in increased motor heating."

dinky