Hello,
we have a big trouble. We’ll set and clear the LEDs by the VMB8PB over RS232 with the VMB1RS.
The module adress is A1
Calculating the checksum:
-All bytes xor
-Invert binary
-Add 1 to the checksum
We send following HEX Code:
Set LED 1 : 0F FB A1 02 F5 01 5D 04
Clear LED 1 : 0F FB A1 02 F5 01 5C 04
When we send the clear LED 1 command, all LEDs clear and when we send set LED 1 command, all LEDs set.
What’s wrong in this HEX Code?
Please help!
Hi EDBErr,
I was looking at the Hex strings, I get the same results than you when computing all - apart from a typo you made in the clear LED: the command is F6, not F5, but as your checksum is correct I guess it’s a typo.
I am wondering if you could check these:
Is the LED status changing working ok when the message comes from modules like vmb1ry/vmb4ry?
If yes, can you capture the message on the bus with the vmb1rs, and compare with yours?
if you get the same problem when the set/clear LED message comes from a relay module, I would rather suspect a cabling problem with the buttons.
That’s what I would look at anyway, but I am not yet expert - maybe Velleman people have other suggestions
Hope this can help,
Chris
Correction to previous post: It’s the SET LED command that is F6…
So I compute the following Hex:
SET Led 1: 0F FB A1 02 F6 01 5C 04
CLEAR Led 1: 0F FB A1 02 F5 01 5D 04
Still probably typos in the initial message, since the instruction is received by the module and acted upon - though incorrectly.
One other question for Velleman people: What happens if the checksum in the RS-232 message is incorrect?
Does it just discard the message? The documentation doesn’t say anything about returning an error to the PC.
If the checksum is incorrect, the Velbus will discard the message.
Please try sending the same packet using the packet editor included in the Velbus beta software. This will make sure there isn’t a problem in your application that might cause unwanted effects.
[quote=“VEL448”]If the checksum is incorrect, the Velbus will discard the message.
Please try sending the same packet using the packet editor included in the Velbus beta software. This will make sure there isn’t a problem in your application that might cause unwanted effects.[/quote]
Where can I get the beta software? Can you send it to my email accout?
info[at]tobias-hocke.de
Thank you for help!
Thank you!
but it’s the same problem 
If I send the command Set LED 1 → All LEDs clear
if I send the command Clear LED 1 → All LEDs set
if I send the command LED 1 blink slow → All LEDs blinks slow
…
:?: Why?
You probably switched the polarity of the leds on your pushbutton module. When you do this, you get the same effects as you described above.
Set 1 = All leds die
Clear 1 = All leds light up
ELedPolarityError 
Yes, it was the ELedPolarityError g
Thank you! Now it works perfect! 