Chapter II
Benchtop multimeter
37
5.4.
Remote programming of the multimeter by a computer
WARNING
:
The accidental sending of certain messages might erase
strategic datas kept in the memory of the multimeter.
In that case, the multimeter might not work properly and it will
have to be sent back to the after sales department or to a
Metrix local agency to be repaired.
The warranty does not cover such a case. Therefore, it is
highly recommended to ensure that the messages whatsoever
are valid and comply with the messages which are given in this
manual.
5.4.1. General about the protocol
The computer is the master of the link during communication; the computer always takes
the initiative of the dialogue.
Each dialogue is in the following form:
- the computer sends an instruction
- the multimeter answers this instruction.
These two messages pass one after the other, since the link is half duplex.
There are three types of dialogues, firstly the check presence dialogue, then the comments
dialogue and the request dialogue.
5.4.1.1. Check presence dialogue
PC
DMM
Meaning
"
Note :
The hex code of the ASCII ENQ character = 05H
The hex code of the ASCII ACK character = 06H
5.4.1.2. Command dialogue
PC
DMM
Meaning
Instruction
Instruction
PC: "Are you there?"
PC: "Execute this comand?"
ENQ
ENQ
Answer 1
Answer 1
DMM : "Yes!"
DMM : "OK!"
ACK
ACK
