SMU RS-485 Model
(See Figure 9)
Hardware:
1) SMU Network Termination Selector -
Each SMU has a
network termination selector in close proximity to the RS-485
network terminal block. The purpose of this selector is to pro-
vide impedance matching on the network to minimize signal
distortion. The two instruments positioned at the network
ends must have their termination selectors "on". The remain-
ing devices on the network must have their termination select-
ors "off". Improper setup of the termination switches could
result in occasional communication problems and reduce how
robust the network system is.
2) SMU Network Bias Selector -
Each SMU has a bias termina-
tion selector in close proximity to the RS-485 network terminal
block. The purpose of the bias selector is to provide stability
to the RS-485 network when communications are idle. The
operator interface on the RS-485 network should have the
bias selector in the ON position. The other devices (slaves)
should have their bias selector in the off position. If a bias
switch is not offered on the operator interface, then set the
bias selectors to the ON position of the two instruments at the
network ends.
3) SMU General Status Indicators -
(viewable through lens)
"Lockout" (orange)
: When illuminated, it indicates that the
SMU has received a signal on the "lockout" input terminal and
that measurement cycles will be prohibited. When flashing, it
indicates that a start (sound) command is being requested
(either manually through Manual Start Switch or from
HMI2/SiloTrack).
SETUP
"Error" (red)
: When illuminated, indicates some form of an
error has occurred, usually cleared by performing a new
sounding measurement.
"Power" (green)
: When illuminated, indicates power is applied
to the SMU, and the micro-controller is performing properly.
When flashing at a fast rate, indicates a sounding is currently
in process.
"Bluetooth” (blue): When illumined, indicates that a Bluetooth
®
device has connected to the SMU.
4) SMU Motor Controls Indicators -
"Cycling" (orange)
: When illuminated, it indicates that power
is applied to the SMU motor.
"Down" (green)
: When illuminated, it indicates that the SMU
plumb bob is descending toward the material.
"Up" (yellow)
: When illuminated, it indicates that the SMU
plumb bob is ascending toward the socket position. When the
unit is powered and the bob is in an idle state at the socket
position, the "Up" (yellow) will be illuminated.
5) SMU Communications Indicators -
SMU Rx (yellow)
: When illuminated, indicates that the SMU is
receiving data in from the RS-485 network.
SMU Tx (orange)
: When illuminated, indicates that the SMU
is transmitting data out onto the RS-485 network.
“Status” (yellow): When flashing, indicates the general well
being of the on board Bluetooth radio. When flashing rapidly,
indicates that the Bluetooth radio is currently being pro-
grammed, and is not available for Bluetooth connections, nor
is the SMU able to take a sounding. Off indicates the Bluetooth
radio is in sleep mode, common during a sounding process.
6) SMU Control Switches -
A sounding can be initiated at the
sensor by pressing the "Manual Sound Switch". A complete
measurement cycle will occur, acquiring a new
measurement value.
6
In addition, the control of the motor can be overridden
by the "Motor Control Switches" (up and down). These are
useful when servicing the SMU's cable, wiper seal or plumb
bobs. Press and hold the "Motor Control Switches" to place
the bob at the desired height, and then remove power from
SMU as you work with the cable. Care should be taken when
these switches are used as all material or socket sensing
capability is disabled; also, do not allow the cable to go slack
or become tangled.
SMU RS-485 Model
(See Figure 9)
Specific Configuration Parameters:
There are many parameters that can be configured into the RS-
485 SMU. The parameters specific to the RS-485 version
include:
1) Communications Selection -
There are three protocols that
can be selected for the RS-485 communications:
l
SiloPatrol
- for use with Monitor's HMI2 or SiloPatrol software.
l
Modbus RTU
and
l
Modbus Ascii
- Generic protocols for
interfacing to the customer's operator interface system.
2) Communications Parameters -
When the SiloPatrol protocol
is selected, the default communications parameter are auto-
matically selected. There are various communications param-
eters available for your Modbus communications to select
from; baud rate, # bit, parity, # stop bit. See Page 8 for
more details.
3) SMU Address -
Each SMU must be given a unique network
address which is configured into the SMU. The network
address corresponds with the HMI2 (or other operator inter-
face) channel number. Communication problems will occur if
multiple SMUs have the same address on the same RS-485
network. See Page 8 for more details on how to configure.
NOTE:
The RS-485 version of the SMU SE and the RS-485
version of Flexar
®
may coexist on the same RS-485 commu-
nications network only if HMI2 is the operator interface.
(Please see Bulletin 344B for specific configuring informa-
tion.) The RS-485 version of the SMU-se and the RS-485
Flexar cannot coexist on the same RS-485 communications
network for any other operator interface.
4) Modbus
TM
Parameters
- See Bulletin 344N to view the
Modbus register map.
Figure 9
