Page | 10
4.
Please note that any open spreadsheets must be closed before attempting to LINK
to Excel again.
VI.
VG03 Protocol
VG-03 units can be accessed over an RS-485 network.
The line parameters are:
Baud rate:
9600
Parity:
None
Data bits:
8
Stop bits:
1
The messages from the master and those returned from the nodes all have the same format:
<AACCIIaabbccddXX>
Where
<
Is the
start
of message character, an open angle bracket character, an ASCII
3𝐶
ℎ𝑒𝑥
AA
Is the
address
of the target node, encoded as two ASCII hexadecimal digits,
01
ℎ𝑒𝑥
to
𝐹𝐸
ℎ𝑒𝑥
. The address
00
ℎ𝑒𝑥
is reserved for the network master, and
𝐹𝐹
ℎ𝑒𝑥
is the broadcast address.
CC
Is the
command
being sent, encoded as two ASCII hexadecimal digits. The
commands include:
01
read a register
02
write a register
03
synchronize clocks
04
poll for measurements
II
is the
index
for the command, usually indicating which register
is being read or written, encoded as two ASCII hexadecimal digits.
aa
Is the most significant octet of the data payload, encoded as two ASCII
hexadecimal digits.
bb
Is the next most significant octet of the data payload. For a 16-bit payload
(register reads and writes), this is the least significant octet.
cc
is the next most significant octet of the data payload. For a 16-bit payload, this is
ignored
