PAGE
6
PC B
OARD
- PC-188 B
ITBUS
I/F
FOR
IBM-PC
O
RDER
NO
. 5904512211
M
AY
2002 - R
EV
. 1.1
The interface with the PC uses a transmission protocol
based on:
-
a data byte
-
a command byte
-
a state byte
-
a pair of bytes reserved for future communications
related to application programs and not directly
connected to the Bitbus communications.
The table below shows the relation between the I/O
port and address according to the selected base address.
Table 4.4.2 Relation between the I/O port and address according
to the base address.
4.5 Message transfer mode
Messages can be transferred between the PC and PC-188
board in either polling or interrupt mode. To select the
mode in which data is exchanged, set jumpers JQ3, …,
JQ15. If no jumpers are installed, data is exchanged in
polling mode, vice-versa if the above-mentioned jumpers
are set, interrupt mode will be used.
The interrupt levels available range from level 3 to level
15. Level 10 and 15 are available only if the board is
plugged in on a AT bus. The figure below shows a selection
guide of the interrupt levels for data transmission and
reception.
NOTE:
The PC should have no interrupt sources with the
same interrupt level. Two free interrupt levels, one
for transmission and one for reception, are required
to operate in interrupt mode.
Figure 4.5.1
ADDRESS
DEFAULT
ADDRESS
REGISTER
DATO
COMANDO
STATO
Aux da 188
Aux a 188
BASE
BASE + 2
BASE + 4
BASE + 5
BASE + 6
208H
20AH
20CH
20DH
20EH
READ/WRITE
READ/WRITE
READ
READ
WRITE
OPERATIONS
ALLOW
JQ9
JQ7
JQ6
JQ5
JQ4
JQ3
JQ10
JQ11
JQ12
JQ15
JQ14
1
Tint
Rint
4.6 Terminal resistor
If the PC-188 board is installed at the ends of the Bitbus
network, the terminal resistors have to be placed on
the DATA and RTS lines by inserting jumpers JT1 and
JT2. If the board is not at the ends of the Bitbus network,
the two jumpers have to stay open.
4.7 Additional functions
Jumpers JA6 can be used if total compatibility with the
PC-44 version of the board (with 8044 Intel inside) is
required.
If the PC extension executes a RXMEM master node at
addresses FFFE and FFFF when JA6 is set to OFF, the
node and configuration will be obtained as happened
with the old PC-44.
On the other hand, if JA6 is set ON, the contents of the
two storage locations will be provided.
Jumper JA7 can be used to activate (JA7 ON) the dynamic
configuration of the board via FIFO. If JA7 is set to OFF
the board is configured according to the jumper settings.
4.7.1 Expansion slot
The board has a Slot#0 expansion slot than can host
serial interface modules such as RS232, RS422/485 and
CANBUS.
To use the expansion slot, move jumpers J7, …, J12 to
locations 2-3 so that DB9 connector (male XP1) can be
plugged in.
As a result, only DB9 connector (female XS1) is available
for the Bitbus.
