HP M2350A Service Manual page 77

Understanding the Computer Module
The Function Cards
Character Format.
Start + [7 or 8 databits] + parity + stop.
Parity = even parity, odd parity, one parity or zero parity.
Internal Connector.
96-way ABC.
External Connectors.
2 x 25-pin "D" Type.
Power Consumption.
4-m
Pmax = 2.4W, Ptyp = 1.5W.
-I- 12V: Pmax = 330mW, Ptyp = 290mW.
-12v: Pmax = 34OmW, Ptyp = 295mW.
All with a RLoad = 3kohm.
This card is a master card, but has no connection to the local bus, as there are no dependant
local cards for the interface. Therefore it may be located in any vacant slot of the computer
module. That is, it may be placed into a spare slot of a cluster used by another master card and
its local cards.
The interface is based around an 8051 microprocessor with a single serial port used in
conjunction with a mono UART to provide a second serial port.
Connection
You can connect the interface card to equipment with the suitable RS232 or RS422 interface via
one of the two 25-pin D-type connectors. You can choose to connect external equipment using
RS232 with hardware handshaking or RS422 data with RS232 hardware handshaking, for longer
distance communications. The data lines for the RS422 use the connector pins not needed for
RS232.
Note
Only the receive part, on both ports of the interface,
is
switched between
.
the RS232 and the RS422 standards. as the interface transmits data on both
standards.
Pinouts
The connector is wired as a standard RS232 connector with the additional data lines used for
RS422 data transmission. See Figure 2-12 for Connector Pin Allocations.
Figure 2-12. Connector Pin Allocations
2-31