Hello!
I am trying
to communicate by a serial interface with an instrument that measures the gas
NO.
In the
attachment please find the manual of the instrument and the bytes that have to
be send/received to/by the instrument. It is based on the NI example “Basic
serial read and write”.
There are 2
command types that can be sent to the instrument:
NORMAL (0x00, 2. byte)
LENGHTY
(0x01, 2. byte)
The first
request must always be NORMAL,
the following commands depend on the answer the instrument provides. There are
3 types of answers from the instrument:
BUSY (0x05,
2. byte), the instrument wasn’t able to maintain the inter-message time of
50ms. No data is returned, the communication mode of the answer is set to BUSY
ACK (0x06, 2.
byte), everything fine, measured data is returned
NAK (0x15, 2.
byte), error
If the
answer is BUSY, the following command must be LENGHTY.
If the
answer is ACK, the following command must be NORMAL.
If the
answer is NAK, the following command must be NORMAL.
For this,
please look at the command handler I also attached.
Between
each command send to the instrument, the user must wait 100ms (time between the
last received bit and the first bit send).
The problem
is now that the instrument does not answer, although I think the order of bytes
I send to the instrument should be fine.
Is there
perhaps any problem of time, or a does my model suffer any other problem I am
not aware of at the moment?
The
attached files are my model and the manuel of the instrument.
It would be
great if anybody could help me.
Thank you
very much for that in advance.
