38
ENAMEL RATER MANUAL: V.10
The jumpers on the micro board must be changed according to the
communications standard used:
RS232
RS422
RS485
J1
C
A
B
J2
B
A
A
J3
B
A
A
SW11/4 on the applications board selects between RS422 and
RS485. When SW11/4 is off RS422 is selected. If RS422 or
RS485 is to be used the plug connecting the socket on the rear
panel to the microboard should be moved from P2 to P3. These
connectors are marked on the circuit board.
7.4
UNI-DIRECTIONAL PROTOCOL
If SW11/3 on the applications board is off (open), uni-directional
protocol is used. As each reading is saved it is automatically sent
down the serial port, if the hardware handshaking line is clear.
7.5
BI-DIRECTIONAL PROTOCOL
If SW11/3 on the applications board is on (closed), bi-directional
protocol is used. As each reading is saved it is stored in an internal
buffer, which is battery backed in case of power failure. When the
enamel rater receives a data request message from the host
computer the data stored in the buffer is sent.
Data Request message:
<40h><01h>
where:
<40h> (1 byte) ASCII character '@'
<01h> (1 byte)
When using bi-directional communications, software handshaking
is available as an option as well as hardware handshaking. If
selected, (SW2/2 closed on the micro board) the XON/XOFF
protocol is used. If XOFF is sent to the enamel rater it must be
followed by XON before any further transmission will occur.