[Dr_C2]

Previously I have mentioned that I and a number of other users of the APB C7042 have been getting good results using an opto-isolator (opto block) between the APB and the RMS computer.

This approach is superior to the basic hard-wired cable approach since it eliminates ground loops and hence reduces the potential for noise spikes and electrostatic damage.

To do this you require an opto-isolator with a USB port on one side and a RS485 port on the other side. The example which I will demonstrate uses the DSD TECH SH-U11F.

A complete setup is shown below:

   

In this thread I will provide some installation details.

[Dr_C2]

Installation of the DSD TECH SH-U11F


1/ Remove the four screws on the back of the DSD TECH opto-isolator, remove the cover, and then fit one of the included jumpers as shown in the photo below. Then re-assemble.

   


2/ Next, connect three short wires between the DSD TECH opto-isolator and the RJ12 socket on the APB C7042. Take care to wire correctly as one of the pins carries +12V so should NOT be connected by error.

I can provide a simple connector board which eliminates any need for attention to wiring details and the use of an RJ12 crimping tool. This is shown on the right hand side in the above photograph.

The wiring diagram for direct wiring or using  the connector board is shown next.

   

3/ Power-up and the job is done.!

[Dr_C2]

Images showing the connector board which fits into the six screw terminals of the DSD TECH opto-isolator at one end and the APB RJ12 socket at the other end.

   

   

[Dr_C2]

And for those who asked for the connector board - I made up a few which are heading for the post office!


c

   

[flat4]

Hello!

I wanted to try this as it seems the smart way to go, but something is going wrong.

Here are a few pics:

   

   

   

I feel like I did the correct wiring, and that there is no driver issue as it is proposed in PCLC.

Any idea about what I did wrong?

[Dr_C2]

Hi Flat4,


Interesting problem.

1/ First, from visual inspection the wiring looks correct.
2/ When connected to the PC, what lights do you see on the opto block? Should show solid red for power plus blinking red/green for data comms. I am guessing you are seeing at least the solid red?
3/ my version of the opto block uses the FTDI chipset and when I look in the windows ‘device manager’ I see the USB port has an FTDI driver installed.
4/ Photos below show my PCLC options/setup screen.

Possibly you have the wrong driver pre-installed?

c

[Dr_C2]

I just checked. There are at least two variants of the DSD TECH opto block.

Mine are SH-U11F with FTDI chipset.

Variant SH-U11H uses the Prolific PL2303GC chipset so it does look like your PC selected the correct drivers for your opto block.

So back to the question … which lights are showing on the opto block?

c

[flat4]

Hi C.

So first things first, I've tried to update the firmware as it actually seemed to be a pretty reasonable path, but it happened that the latest fw has been already installed by win 11.

I happen to have a spare C7042 available brand new, only with fw upgraded, and I got the very same result.

lights behaving:

I do have a solid red, and when I start PCLC, I can see a blinking red.

I also noticed that if I am patient enough, there is very quick green led flashing, and then PCLC says its connected (with an error), but the reality is that debug shows absolutely non communication either way.


   

I see 2 options from there:
- investigate the jumper position which might be required differently from one variant to another
- try to get the SH-11F flavor

any other idea?

[Dr_C2]

Maybe worthwhile double checking continuity between the RJ-12 plug (at the APB end but unplugged) and the terminal block on the opto block?

c

[flat4]

Yes, I did earlier and everything looked fine.

I(ve been comapring the manual of H & F focusing on the jumpers, and I first noticed that jumpers was described in very different ways, and finally understood that I wasn't supposed to use any jumper for RS485 / short distance. So I removed the jumper... and it worked immediately.

If somebody can double check the manual, I would feel better.

If this shows to be stable and safe other time, we then have 2 flavors of the opto solution, but have to be careful about the setup.

I should have been more vigilant from the start, and not trust amazon search engine with only copy / paste "DSD TECH SH-U11F", because you clearly gave the correct designation.