Badger Meter Model 3700 Data Acquisition Server - Manual (Page 10)

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data Logging Period: This option sets the log interval for the
Model 3700. Options range from once per minute to once per
hour. All of the selections are even divisions of one hour. The
Model 3700 calculates the next log time by finding the next
multiple of the log period past the start of the hour. For example,
if the log period is 15 minutes, log readings will be taken at 0, 15,
30 and 45 minutes past the hour. The log period is not calculated
based on 15 minutes after the last reading.
When the Model 3700 is first started, it will take an initial reading
of all the Modbus devices immediately. Following that, the next
log reading will be calculated as a multiple of the log period after
the hour. The initial reading is taken to allow the Model 3700 to
gather information for meters that require demand calculations,
as well as provide accurate information starting when the Model
3700 is booted.
Modbus/TCP access: The Model 3700 has a Modbus TCP
gateway feature that allows other systems to send queries to all
attached Modbus RS485 devices. This feature allows control of
what systems have access to the Modbus TCP gateway feature.
The settings include No Access, Local Subnet Only and Allow
Any. This basic security feature only allows control based on
the IP address of the system making the request. The Modbus
TCP protocol does not have provisions for any authentication
password or other methods of security. By default, the gateway
feature is disabled, and set to No Access.
The Modbus TCP gateway is a feature that allows the Model 3700
to share the attached Modbus RS485 devices with other systems
such as PCs with software and building control systems. The
gateway receives incoming TCP requests, verifies the length of
the packet does not exceed 255 bytes, and forwards the packet
to the Modbus RS485 loop. The gateway does not verify the
contents of the packet, nor the target address specified in the
request. If the Modbus RS485 device sends a valid response
back, the gateway will return this information to the the system
requesting it via TCP. If no response is received, a timeout
failure will be sent to the requester. Because the gateway does
not process the contents of the request or reply, it is possible to
query devices on the Modbus RS485 loop that are not specifically
supported by the Model 3700.
Modbus RS 485 Baud Rate: This feature allows the configuration
of the RS485 serial port speed which the Model 3700 uses to
communicate with modbus devices. Options include 9600,
19200, and Opportunistic/Multi-speed. The default is 9600,
most Modbus devices communicate at this speed as well. In
Opportunistic mode, the Model 3700 will automatically detect
the baud rate of each modbus device, and will continue to
communicate with that specific device at the detected speed.
This feature will allow you to mix multiple devices on the same
RS485 loop with different baud rates. Modbus devices must be
configured at baud rates of 9600 or 19200, other baud rates
are not supported.
NOTE: Modbus device manufacturers usually do not officially
support this configuration, however we have not seen any
problems with this in any of the modbus devices we provide
drivers for. If you are experiencing modbus communications
problems, you should set the baud rate to a fixed 9600 before
troubleshooting.
The Contact Open Threshold can be used in conjunction
with a 20K resistor in parallel with the contact closure. When
the contact is open, the Model 3700 will read 20K, when
closed, it will read <100ohms. If the wire is broken, the reading
will go above 20k ohms, and will cause an alarm condition.
The Pulse count for instantaneous rate value specifies
the number of pulses to use to calculate the instantaneous
rate, min, and max fields in pulse mode.
7. After returning to the device configuration page, click Save at
the bottom of the page to return to the device display page.
Troubleshooting Modbus devices
If the device you have attached does not appear in the Modbus
device list, check the following:
• Verify the + (red), - (black), and Shield connections are correct
on all connections. Look for any connection in the middle
of the loop that may have the wires reversed, or shorted
together. Check the Modbus FAq on the www.dataindustrial.
com website for further details on wiring a Modbus serial
connection.
• Verify the address settings of every Modbus device. No two
devices may have the same address. Note: the Model 3700
uses the address 250 for the internal IO module. Do not
assign this address to any other Modbus device.
• If only one device is not working, try disconnecting all the
other devices on the Modbus loop to isolate the problem. If
possible, bring the failed device adjacent to the Model 3700
and attach it with a short stub of wire to eliminate possible
wiring problems. If the Model 3700 can find a device on the
short stub, the problem is probably a wiring related issue on
the RS485 loop.
• Check to verify the Modbus device is supported by the Model
3700. Usually, the Model 3700 will locate the device and display
Unsupported in the device status column if the device is not
recognized by the Model 3700 firmware drivers. In the lower
right corner of this screen, there is a link that will show a list
of supported devices. Use this to verify the Modbus device
in question is supported by the Model 3700 firmware version.
If not, check for firmware upgrades online with the Firmware
Update configuration page.
• Remember, the Model 3700 may take between 2 and 5
minutes to detect a new device that has been attached to the
Modbus RS 485 loop. Rebooting the Model 3700, refreshing
the device list page, or using the console ‘Modbus status’
menu will not speed up the recognition process.
• Click the Troubleshooting link at the bottom of the Modbus
device list page for further diagnostics.
Modbus Setup
The Modbus setup page provides several options related to the
Modbus RS485 serial port.
Loop Name: This is the name of the Model 3700. This name will
be present on all log file descriptors when uploaded to a central
database website such as BMO. It is helpful to name the Model
3700 based on the physical location of the system, or building.