4
4-4
In the 8099, the RAM is a 16-bit wide memory that is used for running the ac-
tive program, data storage, operating variables and configuration settings. The
8099 data buffers are mechanized as straight buffers because of the Modbus
command-response protocol. The buffers are several times larger than any
anticipated message so no data loss ever occurs.
The 8099's power supply is a switching regulator that converts a unregulated
9 to 32 volt DC input to +5 Vdc to run the 8099's internal logic chips. The +5
Vdc is down regulated to make 3.3 Vdc for the ARM processor and support-
ing chips that run on 3.3 Vdc power. A DC-DC charge pump converter in the
RS-232 transmitter IC makes ± 9 Vdc to operate the RS-232 drivers.