Emerson Commander SK VFD - Need Help with Communications setup with PC

I am hoping somebody on here might be able to help me out with this problem.

I Have an Emerson Commander sk VFD that I would like to hook up to my pc to backup and modify the parameters on. I have Emersons CTSoft program, which is made for this doing this. The problem is I don't have the correct Comms cable needed to hook up the pc to the drive.

Looking through the Commander-SK-Advanced-User-Guide.pdf, it looks like Emerson has two products made for this. The first one they call the CT Comms Cable, which so far as I can tell is an rs232/db9 cable with an rj45 connector on the end of it. In the manual they state they use some of the extra ports on the db9 to provide +10v to the drive. They also say its just meant for commissioning the drive, which is what I need.

They also have a usb-ct-comms-cable, which looks like usb-> Rs485 converter with a power supply built into it.

Emerson wants around $200+ dollars for each of these, which seems ludicrous.



I have a FTDI USB-RS485 cable that I could attach an RJ45 connector to, but I am not sure of how the rj45 connector needs to be wired. (or if it would work)

I think the easier route would be to just convert a normal db9 cable, wiring an rj45 connector connector to the end of it. The problem is I have no Idea how the connector needs to be wired on, and I can't find that info published anywhere.

Can Anyone on here provide me with a wiring diagram on how to make the correct cable? I would have to imagine that somebody has made there own at one point, though I haven't been able to find anything on it.

Upon further reading in the advanced manual, it says "The Commander SK has a standard 2-wire EIA485 half-duplex interface that enables all drive set-up, operation and monitoring to be accomplished"

This would mean that the usb rs485 cable I have should work since it is a standard 2 wire rs485?

Half duplex rs485 only requires 3 wires, TxRx+, TxRx- and ground.

The rj45 pinout on the commander sk:

The following table shows the pin functions for the RJ45 connector on the Commander SK control PCB:
Table 5-2 Commander SK RJ45 pin functions
EIA485
RJ45 connector Pin function
1 Connection for built in EIA485 termination resistor
(120Ω). Connect to pin 8 if termination is required *
2 RXTX (2-wire EIA485 +)
3 0V
4 +24V (±15%) 100mA supply for options
5 Not connected
6 TX Enable
7 RXTX\ (2-wire EIA485 -)
8 Connection for built in EIA485 termination resistor
(120Ω). Connect to pin 1 if termination is required *

I should technically only need to hook up pins 7, 2, and 3 for my purposes. Does this sound right?

Further Update, I think this works, so long as the drive is powered up I can now detect and communicate with it using ctsoft. Once I am sure this is correct I will post the parts I used and the correct wiring req'd.