4-3
4
The RAM is a 8K x 8 static memory that is used to hold the operating
variables and configuration settings. All data stored in the RAM memory
is lost when power is turned off.
The power supply is a switching regulator that converts any unregulated DC
input to +5 Vdc to run the 4863’s internal logic chips. Satisfactory input
range is +9 to +32 Vdc. Due to the use of CMOS circuits, the 4863's power
consumption is very low. Less than 220 mA at 12 Vdc when the outputs are
unloaded.
4.2.2
2363 DIFFERENCES
The 2363 has an serial interface in place of the 4863's GPIB interface. The
Block Diagram for the 4863 OEM Board in Figure 4-2 shows how the serial
interface is connected to the 2363's microprocessor. The RS-232 transceiver
incorporates a charge-pump that provides the
±
8 Vdc necessary to drive the
RS-232 line. The RS-485 transceiver provides the differential transmitter
and receiver functions for the RS-422 or RS-485 differential signal pair. The
remainder of the 2363's internal circuits are the same as those of the 4863.
The serial interface has both RS-232 and RS-485 capability. The RS-232 is
a full duplex interface with transmit and receive signals. There are no
handshaking lines because of the short string lengths of the 2363 commands
and responses. The RS-485 (RS-422) is a half duplex interface with a single
+ and - signal pair. The transmitter is only enabled when the 2363 is
responding to a query. Pullup and pulldown resistors are provided to bias
the RS-485 signals into the logic 1 or mark state and avoid receiver errors.
The serial parameters default to 9600 baud, 8 data bits, no parity and one
stop bit. The 2363 detects which serial input is being used and directs query
responses back on the appropriate interface.
