Xylem H-3521 - Manual (Page 43)

H-3521
SDI-12 Command and Response Protocol 5-13
5.12 Extended Read/Write 4-20mA_Hi and Read/Write 4-20mA_Lo
The H-3521 scales the current Stage data to drive the 4-20mA output. The 4-20mA_Hi and 4-
20mA_Lo
settings control how the Stage data is processed. The 4-20mA_Lo should be set to the
desired Stage corresponding to a 4.00mA output. The 4-20mA_Hi should be set to the desired
Stage
corresponding to a 20.00mA output. These settings are stored in non-volatile EEPROM
within the sensor. Once the new value is written to the EEPROM, a copy is sent to the sensor data
buffer for verification. This data can be viewed by using a subsequent "aD0" command. To
verify these settings any other time, use the “XRIH" or “XRIL” commands. The H-3521 comes
from the factory with the 4-20mA_Hi = 34.6 feet and 4-20mA_Lo = 0.0 feet.(0-15 psi sensor
range)
Command Response Description
"aXRIH!" “a0011" Read 4-20mA_Hi
"aXRIL!" “a0011" Read 4-20mA_Lo
"aXWIHddd!" “a0061" Write 4-20mA_Hi
"aXWILddd!" “a0061" Write 4-20mA_Lo
Where: a is the sensor address ("0-9", "A-Z", "a-z", "*", "?").
XRIH are upper case characters.
XRIL are upper case characters.
XWIH are upper case characters.
XWIL are upper case characters.
ddd is the new value.
This command takes 001 seconds to complete and places 1 value in the data buffer. Use the
“aD0" command to collect and view the slope or offset.
Example of a H-3521 Extended "Read 4-20mA_Hi" command:
Command
Response Time Values Description
"aXRIH!" "a0011" 1 sec 1 Read 4-20mA_Hi
Command Response Description
"aD0!" "a+34.60" 4-20mA_Hi is 34.60
Example of a H-3521 Extended "Write 4-20mA_Hi" command:
Command
Response Time Values Description
"aXWIH34.6!" "a0061" 6 sec 1 Write 4-20mA_Hi and make
new measurement
Command Response Description
"aD0!" "a+34.6" 4-20mA_Hi is 34.6