VISA Serial: Setting DTR State and RTS State to "Unasserted" solves RS232 communication issue; why?

[Ben]

Some widget had inverted hand=shaking lines that were asserted when low.

Just guessing.

Ben

[onnodb · Accepted solution]

I've been in touch with Zaber's technical support, and the conclusion is as follows.

Indeed, the Zaber linear actuators use pin 4 (DTR) to share power between multiple daisy-chained actuators. In our case, the Zabers are connected to the PC like this:

ZABER ==[mini-DIN]==> mini-DIN to serial adapter ==[serial]==> serial-to-USB converter ==[USB]==> PC

The culprit here is the "mini-DIN to serial adapter". It turns out that Zaber uses a custom adapter, which does not connect pin 4 through. In our case, someone put a generic adapter in place, which does connect pin 4 through, leading to the problem described in my post.

Problem solved; thanks a lot for your help!

[Ben]

Thank you for the update (feel free to mark your post as the solution!).

I'm glad you found an appropriate fix.

 It is hard as he#$ to fix a hardware problems with software.

Ben