3
Serial Data Output
The RS232 function will be activated if the RS232 pin is pulled to and asserts at V-.
The serial data sent to SDO pin once every A/D conversion cycle. The data format
complies with JIS 7Bits transmission code with a baud rate of 19230. The host can use
RS232 interface to read the data. A single data packet includes a start bit (always 0), 7
data bits, an odd parity check bit, and a stop bit (always 1). The high and low voltage
levels correspond to DGND and V- respectively. SDO remains at 1 (high) when it is
inactive. Hence the start bit (0) could be used as the triggering signal to begin the
reading process. The following figure shows the data format of a single packet. The
LSB is sent first and the MSB is sent last.
Single packet
0V
p
P 1
D0 ~D6
0
-3V
LSB
MSB
One data block consists of 11 packets, or 110 bits. The following figure shows the
format of a data block. The range packet indicates the full scale range of the meter.
Digit 3 through digit 0 are just the digits on the LCD panel. The function packet
indicates the measurement mode of the meter. Status, option 1 and option 2 give the
status of the meter. CR and LF are delimiters used to separate the blocks.
All packets
p
p
p
0
1 0
1 0
1
range
digit1
status
digit3
digit2
p
p
p
p
p
p
0
0
1 0
1 0
1 0
1 0
1
1
digit0
function
option2
option1
p
p
0
1 0
1
CR
LF
The meter always outputs the current input value to the serial port in spite of HOLD
mode. Each block is repeated twice in one conversion cycle. The detailed data format of
each packet is listed below.
v1.2
20
11/09/06
CYRUSTEK [ Cyrustek corporation ]
