Sutron ModbusLink-M Manual
ModbusLink-M/
ModbusLink-S
OPERATIONS &
MAINTENANCE MANUAL
Part No. 8800-1197
Revision – 1.0
April 1, 2013
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Sutron Corporation, 22400 Davis Drive, Sterling, Virginia 20164
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Table of Contents
1. Introduction..........................................................................................................................2
Features....................................................................................................................................2
2. Unpacking ...........................................................................................................................3
Unpacking................................................................................................................................3
3. Hardware Description..........................................................................................................4
Connectors ...............................................................................................................................4
Terminal Block ........................................................................................................................5
Battery Connections.................................................................................................................5
4. Setup and Operation...........................................................................................................6
Modbus Connections................................................................................................................6
ModbusLink Network basics...................................................................................................6
Setup ........................................................................................................................................8
Configuring ModbusLink ........................................................................................................9
Optional Mounting Bracket Kit (2911-1395)............................................................10
Quick Start Guide ......................................................................................................12
Verifying Communication...........................................................................12
6. Troubleshooting and Maintenance......................................................................................13
Troubleshooting.......................................................................................................................13
Maintenance.............................................................................................................................13
Appendix A ...............................................................................................................................14
Specifications...........................................................................................................................14
Ordering Information...............................................................................................................14
Appendix B ...............................................................................................................................15
Appendix E– Commercial Warranty.........................................................................................16
SUTRON MANUFACTURED EQUIPMENT .......................................................................16
NON-SUTRON MANUFACTURED EQUIPMENT .............................................................16
REPAIR AND RETURN POLICY .........................................................................................16
EXTENDED WARRANTY AND ON-SITE MAINTENANCE............................................16
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1. Introduction
The ModbusLink is a low power multihop mesh network to wirelessly connect modbus sensor(s) to a
Modbus Master. A ModbusLink network consists of one master (ModbusLink-M) connected to a Modbus
Master/logger/data recorder and at least one slave (ModbusLink-S). Each Slave unit can be connected to one
Modbus sensor via either a RS232 or RS485 port. If the ModbusLink-M is unable to reach a Modbus sensor
directly, it will try to discover a route to the destination via intermediate ModbusLink-S modules.
Features
•300 meters LOS range ( longer ranges possible via intermediate nodes/mesh networking)
•Very low power consumption.
•All nodes are capable of routing messages, interfacing with Modbus sensor while staying in
low power mode
•~5 years battery life (included)
•Transparent drop-in Modbus wire replacement. (No special address requirements)
•RSSI level indication to indicate Signal strength.
•Multiple Networks can co-exist without interfering with each other.
•Simple Network commands to configure & maintain network
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2. Unpacking
Unpacking
Remove the ModbusLink-M and ModbusLink-S units from the shipping container and visually inspect the
unit for signs of damage during shipment. Report any such damage to the factory immediately to ensure a
prompt response and resolution. Retain one shipping container in the event a factory return is necessary.
Please note that if a return is required, a return material authorization (RMA) number is required. To get this
RMA number, call the Sutron Customer Service Department at 703 406 2800.
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3. Hardware Description
Connectors
The ModbusLink-M/S modules support the Modbus protocol (RTU mode) over RS-232(default) or RS-485,
selectable via a simple command. The external IP6 rated DB9 connector should be used for communication
with Modbus loggers/Sensors using RS-232. For interfacing with a modbus logger/sensor over RS-485, a 5-
terminal connector is provided. The module can also be provided external power via the 5 pin connector.
Please refer to Table 1 for a detailed description of the connector.
The ModbusLink modules can be connected to a PC via the 10-pin header J4 using a 10pin to DB9F cable
(6411-1382-24) for configuration/debug purposes.
Figure 1 – ModbusLink ports
DB9 Connector
Modbus ( RS232)
PC Configuration port
8-16v Power input
RS485-A/B
RS485-A/B
Modbus (RS-485)
8-16v Power input
6411-1382-24
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Terminal Block
The ModbusLink modules have a 5 position terminal block that supports plug in screw terminals. The screw
terminals are connected to a 5-wire cable which is color coded.
Wire color
Description
White
Modbus over RS485-A
Green
Earth
Brown
Modbus over RS485-B
Red
8-16v dc power input
Black
Power Ground
Battery Connections
The ModbusLink-M/S has an internal battery to power the unit; however, external power (8-16v dc) can be
applied to J3. If external power is applied, the internal battery is automatically cut off and the module runs
off the external supply. The performance/functionality of the module is identical, regardless of the power
input source. If the external supply is removed, the unit automatically shifts to battery power. This transition
is transparent and does not interrupt the normal operation of the module.
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4. Setup and Operation
Modbus Connections
The ModbusLink-M would be connected to a Modbus Data Master/Logger via either the RS232 or the
RS485 port. There is no need for further battery connections.
From the Modbus sensor’s perspective, the ModbusLink-S replaces the Modbus Master on the remote end of
the connection. The Modbus sensors would connect to the ModbusLink-S just as they would to a Modbus
Master/Logger/ data recorder.
The unit supports Modbus (RTU mode) over RS232 or RS485. A simple command can be used to switch
between RS232 and RS485 modes. The ModbusLink-M module is shipped with a NULL modem so that it
can communicate with a Modbus Master or PLC (RS232 mode only). The ModbusLink-S modules can
interface with a modbus sensor using either the RS232 or RS485 port. No NULL modem is required for
RS232 mode.
ModbusLink Network basics
A ModbusLink network consists of ONLY one master (ModbusLink-M) and one or more slave
(ModbusLink-S) modules with the same Network-ID. All slave units must have the same Network-ID as
the Master in order to be able to be part of the same network. For the purpose of simplicity, the Network-ID
can be represented by an imaginary physical wire connecting each ModbusLink module to other
ModbusLink modules (within radio range) having an identical Network-ID, in a mesh-like topology.
Multiple networks each with their own Master and Slave(s) can coexist within range of each other, provided
they have unique Network-IDS. The default Network-ID for all modules (ModbusLink-M and
ModbusLink-S) is ‘15’. No two ModbusLink-M modules with the same Network-ID should be within range
of each other.
When the Modbus Logger sends a Modbus command to the ModbusLink-M module, it extracts the address
information from the command and tries to find a ModbusLink-S module with the same address in the
network. If the destination node is not within radio range of the ModbusLink-M module, it will try to
discover a route via intermediate ModbusLink-S modules. If multiple routes are possible to the destination,
the most efficient route will be selected.
In the above figure, consider the example where the ModbusLink-M module receives a Modbus command
from the Modbus logger addressed to Modbus Sensor #6.The ModbusLink-M broadcasts a route discovery
request to all ModbusLink-S modules in the network. Nodes#2, 3, and 5 receive the discovery request. They
each note that they have a path to M.
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Node# 3, 5 rebroadcast the discovery request. The request is received by Nodes 2, 4 and 6. Node 6 notes it
has a path to M through 2 and sends the route complete message to M through 2. Node 4 also rebroadcasts
the discovery request which is also received by 6; however, it is ignored by 6 since it already has a superior
route.
Once a route has been established, data can be sent through the route to the destination node. Data messages
are never broadcast to conserve power. They are only addressed to a single node (unicast) which could either
be the destination for the message or an intermediate node en-route to the destination as shown below:
The master will send all data destined for node 6, to node 2. node 2 will in turn forward the message to node
6. The other nodes do not play any role in delivering the message to node 6, thus conserving power.
If an intermediate node cannot deliver a message to the next hop, it informs the sender, which starts a new
route discovery.
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Setup
Each ModbusLink-S module in the network must have a unique node address. The address of the
ModbusLink-S module must match that of the modbus Sensor connected to it. The ModbusLink-S can be
configured to operate in Auto address mode or it can also be assigned a static address. The ModbusLink-M
module does not need any address configuration.
The ModbusLink module is shipped with an internal D-Cell battery that is used to power the radio and
communications with a local modbus sensor (if connected). To prevent damage, the internal battery is
disconnected before shipping. Unscrew the lid and connect the battery connector to J5 as shown in the figure
below. If, using automatic Node address configuration(described below), ensure that the Modbus sensor is
connected to the ModbusLink-S at power up . Also ensure that the modbus communication parameters like
baud, parity etc of the sensor are the same as ModbusLink-S module. If the parameters are different from the
default settings of the ModbusLink-S, refer to the Appendix for details on how to change the Modbus
communication parameters.
If configured to operate in the automatic address mode, The ModbusLink-S modules will automatically scan
the RS232/RS485(based on configured port) ports for a Modbus sensor, during the power up sequence. On
receiving a response from the sensor, the ModbusLink-S Node sets it own address to that of Modbus sensor
(If no sensor is found, the ModbusLink-S will retry after an hour. If the automatic configuration is not
desired, the ModbusLink-S node can be assigned a static address. The static address assigned to each node
must be unique throughout the network and match the address of the local modbus sensor connected to it
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Replace the enclosure lid and tighten the screws
To prevent damage while shipping, the antenna is not connected to the module. Please screw the antenna to
the RP-SMA connector on the top of the enclosure, till it is secure. DO NOT OVERTIGHTEN THE
ANTENNA to prevent damage to the RP-SMA connector.
Configuring ModbusLink
The ModusLink module can be configured using a 10-pin to DB9 cable (6411-1382-24) connected to J5.
Any terminal program like HyperTerminal (Baud = 5700, parity = none, Handshaking = none) can be used to
configure the modules. The general command syntax is
<command> = <value><CR><LF>
Command
value
Response
Description
AT
--
OK
Test RS232
communication with
module
Modbus Com = <value>value = RS232, RS485 > Modbus Com = value
Where value = the new modbus com
port
Set Modbus
communication port to
either RS85 or RS232
Modbus Baud = <value>
<value>=57600 , 38400 ,
19200, 9600, 4800
>Modbus Baud = value
Where value = new baud rate
Set the baud rate for
the Modbus port
Modbus Parity =<value>
<value> = odd, even,
none
>Modbus Parity =value
Where value = new parity setting
Set the parity for
Modbus
communication
Modbus Device = <value>
<value> = master : Set
Modbus device as
ModbusLink-M
<value> = slave : Set
Modbus device as
ModbusLink-S
>Device type = value
value = Master if device is configured
as a Modbus master
value = slave if device is configured as
a Modbus master
Configure the module
as ModbusLink-M or
ModbusLink-S
(this command
requires the module to
be power cycled to
take effect)
Battery Connector (J5)
Antenna connector
10
Command
value
Response
Description
AT
--
OK
Test RS232
communication with
module
Node Address =<value>
<value> = 0 : automatic
node address
<value> 1 thru 247 :
Static address range
>Node Addr = value
Where value = new address assigned to
the Node
Set the node address to
either automatic or
static address
NwId=<value>
<value> = 1 through 15
>NwID = <value>
value = new value for Network ID
Set the network ID.
Must have the same
value for all modules
in the same network
Nw Scan
--
>
Node Address=addr, Hops= hops
returns the address and hop count for
each node
Performs a live Scan
and report the address
and hop count for all
nodes in the current
network
ver
--
>NW Stack Ver=x.xx
>Modbus Stack Ver=x.xx
Returns the version
number of the modbus
stack and network
stack
Blink Led =
<addr>,<time>
<value> = remote node
address
<time> = duration in
seconds to keep blinking
the LED on remote node.
If time = 0 , the Led will
blink forever
>OK :
Node blink command sent successfully
>ERROR : Destination not found
Unable to locate remote node
Blink the Red LED on
remote node for a
predetermined amount
of time
Factory Defaults =!Sutron!
-- OK Restores all settings to
factory defaults
Optional Mounting Bracket Kit (2911-1395)
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The optional mounting bracket kit provides an easy way to mount the ModbusLink modules to a 1.5"
standard pipe. The kit includes the mounting plates, alignment bracket and u-bolts/hose clamps and screws to
Panel for mounting to a
pole using Hose clamps/U
bolts.
(
refer datasheet for
ModbusLink specific
mounting kit part numbers
12
fasten the plate to the ModbusLink modules. The mounting plates are designed to allow other u-bolts and/or
hose clamps (not provided) to allow mounting to 1" and 2" pipes as well.
Quick Start Guide
The configuration of ModbusLink modules can be broadly classified into two categories
•Generic configuration applicable to both ModbusLink-M and ModbusLink-S.
•Node Address config applicable only to ModbusLink-S modules.
Generic Config
•Open the enclosure lid and connect the module to a PC via the 10-pin to DB9 cable. On the PC
open HyperTerminal (baud 57600, parity = None, Handshaking = none) or any other terminal
program.
•Power the module either by connecting the battery or applying 8-16v to the appropriate terminal
block leads
•Issue a test communication command “AT”. The module must respond with “OK”
•To use Modbus in the RS485 mode, issue command “Modus Com = RS485”. The default is RS232
•To change Baud issue command “Modbus Baud = <baud>”. Refer to the command table for
supported baud rates
•To change the parity issue command “Modbus Parity=<parity>” Refer to the command table for
supported parity types
•To change the Network ID, issue command NwID=<Network Id>
•Power cycle the device
Node Address config
The ModbusLink-S modules can be configured to operate in 2 address modes
1) Static address mode
2) Automatic address mode (default)
Static Address mode
Assigning any node a Non-Zero Node address make is operate in the static address mode.
To change the Node address, please follow the following steps
•Issue command Node Address = <addr>, where addr is the static address of the module. This
address must match the address of the local Modbus Sensor. To revert to automatic address mode,
set the Node address to 0.
•Power cycle the module
Verifying Communication
If the slaves are configured to operate in the automatic address mode, it is advantageous to have the modbus
sensors connected to the slaves before powering up the modules.
After powering on the ModbusLink-M and ModbusLink-S modules, wait for about 2 minutes for the slaves
to finish scanning for a Modbus Sensor(automatic address mode only). Issue command “NwScan” and wait
for a few minutes for the scan to complete. Ensure that all the nodes are being reported in the scan.
To visually Identify a node issue command “Blink Led = <addr>,<duration>”. This will blink the Red LED
on node with address = addr for duration seconds
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6. Troubleshooting and Maintenance
Troubleshooting
The following checklist will help in troubleshooting problems:
Problem
Possible Cause
No response
from module
(PC config)
Ensure that the module is powered and the baud rate and
parity are correctly set on the PC side
Unable to query
remote Modbus
sensor
Ensure that the Modbus baud, parity settings on the
sensor/logger and the ModbusLink-S/ModbusLink-M are
identical
Ensure that the Modbus Device (Rs232/RS485) settings are
correct
If using Static address’ ensure that the address assigned to
the slave matches the address of the Modbus sensor
If using automatic address mode, ensure that the Modbus
sensor is powered and connected to the ModbusLink-S
module before powering it up.
Power cycle the
ModbusLink-S module.
Ensure that all the modules have the same Network ID
Ensure that the Antenna is properly secured
Intermittent lost
data Ensure that the Antenna is properly secured and that LOS
link is available between the node and its neighbor
Nw Scan
reports the
Node address as
a large junk
/negative
number
The Node has been configured in automatic address mode
and was unable to find a Modbus sensor connected to it.
Maintenance
Maintenance of the unit should be performed at regular intervals which are dependent upon the conditions of
use. Typical maintenance for the unit consists of checking the wiring to make sure it is not corroded or
frayed and examining the unit to ensure that there is no physical damage.
14
Appendix A
Specifications
Network
Frequency
2.4 GHz license free band
Range
300m LOS
Network type
Ad-hoc homogenous mesh
Power consumption 450µA @ 3.6v average (~3mA for ModbusLink-M if
using modbus over RS485)
Battery Life
~ 5 years (internal battery included)
RF power
3dBm (max)
Antenna
5 dBi external antenna
Leds
3 LEDs (RF, Status, Errors)
Modbus
Modbus protocol
RTU mode
Communication
RS232 / RS485
Baud Rates
4800,9600, 19200, 38400, 57600
Parity
Odd, Even, None
Mechanical /Environmental
Enclosure
5” x 4’ x 2” NEMA rated enclosure
Weight
~400gms (including battery)
Temperature
-40C to +60C
Power Input (optional)
8-16v
Pin 9 (DB-9 connector)
Antenna Connector
RP-SMA Female
Ordering Information
ModbusLink
ModbusLink-M
ModbusLink Master
ModbusLink-S
ModbusLink Slave
Accessories
6411-1382-24
DB9 cable for configuration
6661-1306-20
8.5db Omni kit w/20 ft. low loss cable
2911-1395-1
ModbusLink Pole Mounting Kit (hose clamp)
2911-1395-2
ModbusLink Pole Mounting Kit (U Bolt)
2271-1190
Mounting feet (Panel Mount)
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15
Appendix B
Customer Service Representatives routinely handle a wide variety of questions every
day. If questions arise, please feel free to contact me or one of the Customer Service
Representatives. We are available from 8:00 am to 5:00 pm Monday through Friday
and will be happy to take your call.
We can answer most sensor and interface questions on the first call. If we cannot
quickly answer a question on an interface, we will work with you until we find a
solution.
Sometimes a problem is application related. Although we pride ourselves on handling
95% of application related questions over the phone, we maintain constant contact
with our Integrated Systems Division and Engineering Division for additional
assistance.
Introductory Training
Training is an important part of the Sutron Customer Service philosophy. The Sutron
training policy is simple---If you buy Sutron equipment, you get Sutron training!
Without the proper training, you cannot take advantage of the benefits and
advantages that Sutron equipment provides. We often supply on-site introductory
training at your facility for no charge. You provide the classroom, students,
equipment, and coffee---we'll provide the instructor.
On-Site Visits
Of course not all problems can be fixed over the phone. Sometimes a customer needs
an on-site technician to identify site related problems or troubleshoot a network.
Sutron can provide these services at a reasonable cost. Call for details.If you would
Thanks again for your order,
Paul Delisi
Customer Service Manager
Sutron Corporation
16
Appendix E– Commercial Warranty
SUTRON MANUFACTURED EQUIPMENT
THE SUTRON CORPORATION WARRANTS that the equipment manufactured by its manufacturing
division shall conform to applicable specifications and shall remain free from defects in workmanship and
material for a period ending two years from the date of shipment from Sutron’s plant.
Sutron’s obligation under this Warranty shall be limited to repair at the factory (22400 Davis Drive, Sterling,
VA 20164), or at its option, replacement of defective product. In no event shall Sutron be responsible for
incidental or consequential damages, whether or not foreseeable or whether or not Sutron has knowledge of
the possibility of such damages. This warranty shall not apply to products that have been damaged through
negligence, accident, misuse, or acts of nature such as floods, fires, earthquakes, lightning strikes, etc.
Sutron’s liability, whether in contract or in tort, arising out of warranties or representations, instructions or
defects from any cause, shall be limited exclusively to repair or replacement parts under the aforesaid
conditions.
Sutron requires the return of the defective electronic products or parts to the factory to establish claim under
this warranty. The customer shall prepay transportation charges to the factory. Sutron shall pay
transportation for the return of the repaired equipment to the customer when the validity of the damage claim
has been established. Otherwise, Sutron will prepay shipment and bill the customer. All shipments shall be
accomplished by best-way surface freight. Sutron shall in no event assume any responsibility for repairs or
alterations made other than by Sutron. Any products repaired or replaced under this warranty will be
warranted for the balance of the warranty period or for a period of 90 days from the repair shipment date,
whichever is greater. Products repaired at cost will be warranted for 90 days from the date of shipment.
NON-SUTRON MANUFACTURED EQUIPMENT
The above Warranty applies only to products manufactured by Sutron. Equipment provided, but not
manufactured by Sutron, is warranted and will be repaired to the extent of and according to the current terms
and conditions of the respective equipment manufacturers.
REPAIR AND RETURN POLICY
Sutron maintains a repair department at the factory, 22400 Davis Drive, Sterling, VA 20164. Turn around
time normally ranges from 10-30 days after Sutron receives equipment for repair. Call Customer Service at
(703) 406-2800 for a Return Material Authorization (RMA) number. Return the defective equipment to
the factory, transportation charges paid.
EXTENDED WARRANTY AND ON-SITE MAINTENANCE
Extended warranty and on-site maintenance contracts are available. Price quotations may be obtained from
Sutron customer service representatives.
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