Search found 4 matches

by Vdhproducts67
Wed Feb 21, 2018 11:36 am
Forum: PicoScope 6 for Windows
Topic: Serial decoding MODBUS RTU Frame start/end time
Replies: 10
Views: 2344

Re: Serial decoding MODBUS RTU Frame start/end time

Dear Gerry, In the TIA-485-A March 1998 (Reaffirmed december 2012) "Figure 2. signaling sense" it shows that "A" is positive (non-inverting) pin. I attached a 2003 version PDF. I think the confusion is about the binary "0"="ON" (VA > VB) and "1"="OFF" (VA < VB). I am glad there is an invert function...
by Vdhproducts67
Wed Feb 21, 2018 9:09 am
Forum: PicoScope 6 for Windows
Topic: Serial decoding MODBUS RTU Frame start/end time
Replies: 10
Views: 2344

Re: Serial decoding MODBUS RTU Frame start/end time

Hello Gerry, Thank you for your reply. First question: In the attached picture you can see my serial decode setup. In the previous attached datafile you can see that +ve(A) is blue. So this should work like you mention. Why do I then have to check the "invert" box in the serial decode setup to get t...
by Vdhproducts67
Thu Feb 15, 2018 10:19 am
Forum: PicoScope 6 for Windows
Topic: Serial decoding MODBUS RTU Frame start/end time
Replies: 10
Views: 2344

Re: Serial decoding MODBUS RTU Frame start/end time

Addition to second question:
The inter-frame delay (t3.5) for bitrates higher than 19200 is 1.750ms(modbus protocol dec 2006). Picoscope's serial decoding is correct.

Would it be possible to make this inter-frame delay adjustable?

Kind regards,
Peter van Riessen
VDH Products
by Vdhproducts67
Wed Feb 14, 2018 9:45 am
Forum: PicoScope 6 for Windows
Topic: Serial decoding MODBUS RTU Frame start/end time
Replies: 10
Views: 2344

Serial decoding MODBUS RTU Frame start/end time

When using the serial MODBUS RTU decode function in Picoscope 6.13.2.3439 Beta I encounter some problems. 1. Why do I have to invert the A-B RS485 signal for proper decoding? 2. How is the start and end frame time calculated. I get an "invalid start" and "invalid end" error. If I calculate the 3.5 c...