Parport to 7i92

More
06 Jun 2022 15:49 #244678 by scotth

Please Log in or Create an account to join the conversation.

More
10 Jun 2022 00:17 #244837 by andypugh
Replied by andypugh on topic Parport to 7i92
You might need a common signal ground between the VFD and control PC.
Many converters connect only the two data wires and ground is somewhat assumed.

I have found it better to explicitly wire it.

Please Log in or Create an account to join the conversation.

More
10 Jun 2022 06:10 #244847 by scotth
Replied by scotth on topic Parport to 7i92
My last 485 project was a Modbus master and three slaves, the network covered about fifteen hundred feet or 460 meters. Through a machine shop and heat treat facility. I used a Beldon twisted pair with shield and 120 ohm terminators at each end.
Controlling two Allen Bradley VFDs keeping them in sync.

Properly terminated noise should not be a problem. If you have a scope, put it on the lines and tell us what it looks like.

Please Log in or Create an account to join the conversation.

More
10 Jun 2022 06:47 - 10 Jun 2022 07:56 #244849 by looping
Replied by looping on topic Parport to 7i92
In t500-hotbus/rs485-wiring-guide.pdf from the link above I discover the requirement for wiring.
My wire is about 1m long, shielded, not twisted from my scrap box. It's not 120 ohms impedance. During my previous tests, I replaced it with a thicker one, add termination resistor, add and removed the GND link with no better result. I need to find a 120 ohms to be sure.

From the oscilloscope, it seems hy_vfd it trying to read ACV from the VFD every 600ms when no response: see HY_22Kw.jpg. The debug file shows that hy_vfd is picking up the noise as a response.

See HY_15Kw.jpg when my other HY is responding. Much more traffic.
Attachments:
Last edit: 10 Jun 2022 07:56 by looping.

Please Log in or Create an account to join the conversation.

More
10 Jun 2022 17:37 #244892 by scotth
Replied by scotth on topic Parport to 7i92
Put your B probe on the bar TX line. Look at "A" TX and "B" bar TX to see transmitted noise.

Please Log in or Create an account to join the conversation.

More
12 Jun 2022 12:31 #244991 by looping
Replied by looping on topic Parport to 7i92
Here is A and B
Attachments:

Please Log in or Create an account to join the conversation.

More
12 Jun 2022 13:30 - 12 Jun 2022 13:35 #244993 by looping
Replied by looping on topic Parport to 7i92
On the PCB, I located the rs845 transceiver chip : U4
Many rs485 transceiver have the same pinout as this one thvd8010.

Assuming this, it seems the query from the computer seems to be correctly decoded on the pin #1 : R (I didn't trace it yet, up to the MCU).
But I have level changes on pin #2 (Receiver enable, active low) neither on pin #3 (Driver enable, active high) or pin #4 (Driver data input)
Attachments:
Last edit: 12 Jun 2022 13:35 by looping.

Please Log in or Create an account to join the conversation.

More
12 Jun 2022 13:34 #244994 by looping
Replied by looping on topic Parport to 7i92
Here are the signals on the 1.5kw for pins 1 to 4.
Attachments:

Please Log in or Create an account to join the conversation.

More
13 Jun 2022 20:28 - 13 Jun 2022 20:28 #245086 by looping
Replied by looping on topic Parport to 7i92
Here are the signals on the 2.2kw
DE signal (Driver enable, active high) remain low. Does it mean that the rs485 is not enabled !?

PS:
On June 5, I wrote thant I could execute some command on the VFD using SpindleTalker2. Today I couldn't succeed starting the spindle niether had a single response fron it. (I'm still using the shielded wire from my scrap box)
Attachments:
Last edit: 13 Jun 2022 20:28 by looping.

Please Log in or Create an account to join the conversation.

More
13 Jun 2022 21:02 #245088 by scotth
Replied by scotth on topic Parport to 7i92
Try A channel on RS+ and B channel on RS- .
Lower right-hand side of control terminals.

They should mirror, and anything else is noise and should be rejected.

Please Log in or Create an account to join the conversation.

Moderators: cmorley
Time to create page: 0.152 seconds
Powered by Kunena Forum