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The communication port mating connector is sup-
plied with the RS232 PCB (AMP/Cannon or
equivalent 15-pin "D" type male connector).
For example, the Transmit data signal from con-
troller (pin 2) must be connected to the host com-
puter's receive data line (pin 2) and vice versa.
Consult the host computer's instruction manual for
its serial port connections.
NOTE
Varian cannot guarantee compliance with FCC
regulations for radiated emissions unless all exter-
nal wiring is shielded, with the shield being termi-
nated to the metal shround on the 0-subconnector.
The cable should be secured to the connector with
screws.
Serial Communication Descriptions
This unit can communicate by two different proto-
col:
− protocol (old system) "letter"
− "Window" protocol (new system).
These two protocols can be used as well with 232
or 485 media.
NOTE
Please use "Window" protocol for new develop-
ment.
WINDOW PROTOCOL
Description
Communication Format
• 8 data bit
• no parity
• 1 stop bit
• baud rate: 600/1200/2400/4800/9600 pro-
grammable
Communication Protocol
The communication protocol is a MASTER/SLAVE
type where:
• Host = MASTER
• Controller = SLAVE
The communication is performed in the following
way:
1.
the host (MASTER) send a MESSAGE + CRC
to the controller (SLAVE);
2.
the controller answer with an ANSWER + CRC
to the host.
The MESSAGE is a string with the following format:
<STX>+<ADDR>+<WIN>+<COM>+<DATA>+<ETX>+<CRC>
where:
When a data is indicated between two quotes ('...')
it means that the indicated data is the correspond-
ing ASCII character.
<STX> (Start of transmission) = 0x02
− <ADDR> (Unit address) = 0x80 (for RS 232)
<ADDR> (Unit address) = 0x80 + device num-
ber (0 to 31) (for RS 485)
− <WIN> (Window) = a string of 3 numeric char-
acter indicating the window number (from '000'
to '999'); for the meaning of each window see
the relevant paragraph.
− <COM> (Command) = 0x30 to read the window,
0x31 to write into the window
− <DATA> = an alphanumeric ASCII string with
the data to be written into the window. In case
of a reading command this field is not present.
The field length is variable according to the
data type as per the following table:
DATA TYPE
Logic (L)
Numeric (N)
Alphanumeric (A)
− <ETX> (End of transmission) = 0x03
− <CRC> = XOR of all characters subsequent to
<STX> and including the <ETX> terminator.
The value is hexadecimal coded and indicated
by two ASCII character.
The addressed SLAVE will respond with an AN-
SWER whose structure depends from the MESSAGE
type.
When the MESSAGE is a reading command, the
SLAVE will respond transmitting a string with the
same structure of the MESSAGE.
Using the RS 485 interface, the message structure
remains identical to the one used for the RS 232
interface, the only difference being that the value
assigned to the ADDRESS <ADDR>.
68/74
TECHNICAL INFORMATION
NOTE
FIELD
VALID
LENGTH
CHARACTERS
1
'0' = OFF
'1' = ON
6
'-', '.', '0' . . . '9' right justified
with '0'
10
from blank to '_' (ASCII)
NOTE
87-901-010-01
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