User`s guide

Chapter 11: Rackmount Ethernet Master
Memory Board
Memory Board
The REM is available with 2 MB, 4 MB, or 8 MB (MB = megabyte) battery-backed RAM
Memory PCB's. The RAM is battery-backed and is supported when AC power is
disconnected from the unit for up to two years (depending on the time the unit is
disconnected from AC power). The alkaline battery is not recharged on the PCB. Size
requirements can be computed using the following record size specifications.
• Each PLU record uses 330 bytes.
• Extra Text uses up to 3240 bytes (not including 13 bytes overhead). The extra text
formula is:
(Lines x #characters per line)+ 13= #bytes required . For example: 10
lines x 42 char/line = 420 bytes per record. (60 lines max.)
• Nutrifact records use 393 bytes per record.
• Graphics can be up to 6k per record.
For example:
1000 PLU records: 330k
1000 ET records: 433k
1000 NF records: 393k
100 Graphics: 600k
Total 1756k (approximately 1.7 MEG)
Host Interface
Two types of serial host hardware interfaces are available on the host port: RS232 and
RS422 Multidrop. The host can also communicate using standard Ethernet Host
interfaces. The serial interface is selected by connecting to the appropriate pins on the
DB9 connector on the I/O Connector PCB. The RS232 interface is for a single device
connected directly to a host computer or modem for full asynchronous communication.
The cable length using the RS232 interface is limited to 100 feet (30.5 meters). RS422
must be used when the distance of the cable may exceed 100 feet, or if there will be
more than one master or standalone scale connected on the host network. The
maximum cable length when using RS422 is 1200 feet (366 meters). The REM is
multi-tasking and can perform complete host communication in the background while
servicing requests from the satellite scales.
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