Varian Turbo-V 250 series, Instruction Manual

Page: 64 / 79

TECHNICAL INFORMATION
57 87-900-852-01 (B)
RS 232 Communication Port
Communication serial port connections and minimum
connection configuration are shown in the following
figures. The communication port mating connector is
supplied with the RS 232 PCB (AMP/Cannon or
equivalent 9-pin “D” type male connector). The external
cable (not supplied) between the host computer and
the controller doesn’t require any crossed wires so that
signals are connected correctly.
NOTE
Varian cannot guarantee compliance with FCC regulations
for radiated emissions unless all external wiring is shielded,
with the shield being terminated to the metal shroud on the
O-subconnector. The cable should be secured to the
connector with screws.
RS 232 Communication Descriptions
Communication format:
•
8 data bit
•
no parity
•
1 stop bit
•
The baud rate is programmable via front panel from
600 to 9600 baud. The controller is factory-set for
9600 baud operation.
NOTE
When a baud rate of 2400, 4800, 9600 baud is used,
the requested information from Host to controller must
be sent with a minimum interval of 1 second to avoid
the controller hang-up.
Communication protocol:
Host = Master
Turbo-V 250 Controller = Slave
The communication is performed in the following way:
Host Turbo-V 250 controller
Communication RS 232 serial port connections
Minimum connection configuration
Request is an ASCII character identifying the action that
must be performed by the controller or the requested
information.
Allowed ASCII characters:
•
"A" = START
•
"B" = STOP
•
"C" = Low Speed ON
•
"D" = Low Speed OFF
•
"E" = Request for operational parameters
•
"F" = Pump times zeroing
•
"G" = Parameters reading
•
"H" = Parameters writing
•
"I" = Request for operating status
•
"J" = Request for numerical reading
•
"K" = Request for counters reading.
CRC corresponds to the sum (with inverted sign) of all the
preceding bytes.
e.g., the START command "A" in ASCII code = 41;
inverted it will be: FF + 1 - 41 = BF.