7 |
P a g e
or visit www.gropoint.com/support
RIOT Technology Corp.
| #220
–
10114 McDonald Park Rd | North Saanich V8L5X8, BC Canada | +1.250.412.6642
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©2020,
RIOT Technology Corp.
Wiring Connections
Wire Colour Function
Brown
+ Power (6.5V-18VDC)
White
MODBUS/RS485 D-
Blue
MODBUS/RS485 D+
Black
SDI-12 I/O
Gray
Ground
*Standard cable wire colours. Other cable options available (may have different colours)
Optional M12 5-Pin Male A-Code Connector
Pin # Colour Function
Pin Locations
1
Brown + Power (6.5V-18VDC)
2
White MODBUS/RS485 D-
3
Blue
MODBUS/RS485 D+
4
Black
SDI-12 I/O
5
Gray
Ground
*Available as field installable option, with screw terminal wire
termination.
Reading Methods
The GPLP Lite multi-segment soil moisture profiling probes use the SDI-12 Protocol for serial
communications. The sensors conform to V1.3 of the SDI-12 protocol. Serial communication
settings are 1200 baud, 7 data bits, even parity, 1 stop bit. SDI-12 commands must begin with
a minimum 12.5 ms break signal, followed by an 8.3 ms mark space, then the command char-
acters. Note: for a complete description of the SDI-12 communications protocol, please refer to
http://www.sdi-12.org/specification.php
GroPoint™ Profile
probes may be read with any compatible SDI-12, Modbus or RS485 logger,
communications interface, or reader unit. (RIOT offer accessories for reading SDI-12 sensors:
the GroPoint™
GP-DU SDI-12 Display Unit (Part# 2628)
is a handheld display unit for
taking field readings
; the GroPoint™
GP-USB Connect - SDI-12 Sensor (Part# 6300)
is a
USB to Sensor interface that connects sensors directly to application software on a USB
equipped computer.
GroPoint™ accessories are listed in appendix E of this manual.
Sensor Start Up Time / Measurement Time
Important Things to Note
The time from application of power to the SDI-12 power bus until the sensor is ready to receive
a command is approximately 75ms. The reported measurement time in response to the
M!
measure command (where “a” is sensor address) is 002 seconds. Actual measur
ement time is
approximately 100ms per segment, so the three segment probe measurement will typically be
less than one second from the end of the
aM!
command response (a0021<CR><LF>) until the
measurement finished service request (a<CR><LF>). Power current consumption is at an