Rice Lake MSI6260cs Digital Crane Scale Operator Manual - Manual (Page 10)

Page 10 MSI-6260CS Crane Scale™ • User Guide
6260CS Crane Scale
RF SCALE INSTRUMENTATION
SECTION 2 – RF SCALE COMMUNICATIONS
INTRODUCTION - THE CELLSCALE SYSTEM
The 6260CS is a key component of the MSI CellScale ™ System. The CellScale system uses frequency hopping
spread-spectrum RF Modem technology transmitting in the 2.4 GHz ISM band.
RF Modems have been problematic as the RF bands are very hostile, corrupted by noise, path loss and inter-
fering transmission from other radios. Even in a pure interference-free environment, radio performance faces
serious degradation through a phenomenon known as multipath fading, a problem particularly prevalent for
indoor installations. Multipath fading results when two or more reflected rays of the transmitted signal arrive
at the receiving antenna with opposing phase, thereby partially or completely cancelling the desired signal.
Spread spectrum reduces the vulnerability of a radio system to both interference from jammers and multipath
fading by distributing the transmitted signal over a larger region of the frequency band than would otherwise
be necessary to send the information. This allows the signal to be reconstructed even though part of it may be
lost or corrupted in transit.
Spectrum has been set aside at 2.4GHz in most countries for the purpose of allowing compliant spread spec-
trum systems to operate freely without the requirement of a site license. In the USA, there are absolutely no
site licensing requirements. The CellScale system is also programmable for use in most European countries.
Please contact MSI for worldwide compliance information.
NETWORK DESCRIPTION
The CellScale system uses frequency hopping which is produced by transmitting the data signal as usual, but
varying the carrier frequency rapidly according to a pseudo-random pattern over a broad range of channels, in
this case 86 discreet frequencies. These 86 frequencies are combined in different “hopping patterns” to provide
64 separate networks. The CellScale network uses a ‘Star’ network topology. One unit, usually the CellScale,
is designated a ‘Master’. The Master transmits a sync pulse on a regular basis, providing synchronization of all
remotes in the designated Network. Thus it forms the center of a cell. MSI provides four products capable of
being the master unit: the CellScale Model 9000, the 9300 Crane Scale, the 9260 Ruggedized Crane Scale, or
the 6260CS Crane Scale. Up to 16 remotes can access the master unit. Current MSI provided remote devices
include the 3750CS Indicator, the 9750A Handheld Indicator, the 9850 Indicator, and the 9020 CellModem.
Multiple remotes can coexist on one network, or can be easily switched to other networks as required.
The CellScale system uses TDMA (Time Division Multiple Access) to arbitrate between multiple remotes.
Each remote is assigned a specific time slot thus guaranteeing data throughput.
NETWORK EXPANSION
You can expand your system with virtually unlimited combinations of additional CellScales™, CellModems,
and CellScale Indicators (3750CS, 9750A, and 9850).
You can also expand your system with any component that features an RS-232/422/485 input/output (I/O) port:
desktop/laptop computers, printers, scoreboards, relay boards and many others.
There are three ways to connect additional components to your cellular weighing network.
1) Via MSI-3750CS, 9750A, or 9850 Indicators:
RS-232 components can be linked directly to the Indicator Comm Ports with a cable. The 9850 offers two
available Comm ports, one of which is software configurable to RS232/422 or 485. The 3750CS offers 1
RS-232 port.
2) Via CellModem, MSI-9020:
Components can be linked to a remote radio modem, the MSI-9020 CellModem. It enables wireless cel-
lular communication with CellScales™ and the rest of your cellular weighing network. CellModems are
linked via RS-232/422 to peripheral equipment. If necessary, a USB to serial converter can be used for
Computers not equipped with RS-232 serial ports. MSI recommends Keyspan™ products such as the
USA-19HS for this purpose.
In conjunction with the 9020, MSI offers an advanced software solution to interface with the 6260CS,
“CVM”. CVM provides a virtual meter interface for multiple scales and provides datalogging and other
advanced features for computer/scale systems.