Teledyne Refrigerated Sampler 6712FR - Manual (Page 132)

6712FR Refrigerated Sampler
Section 5 Extended Programming
5-44
5.21 Pressurized Lines The sampler can obtain samples from pressurized lines, as long
as the line pressure remains below 15 PSI (pounds per square
inch). Pressures greater than 15 PSI may prevent the sampler
from purging the suction line; moreover, extreme pressures can
force liquid past the pump, even when the pump is not running.
For more consistent sample volumes from lines under constant
pressure, calibrate the samples. Teledyne Isco does not rec-
ommend sampling from pressurized lines.
5.22 Command Driven
Operation
The 6712 controller can be used as a slave to an external con-
troller. The external controller is responsible for determining
when to take a sample, how much volume to pump, and where to
put the sample. The external controller directly interfaces to the
sampler via an RS-232 communications port at 2,400-19,200
baud, 8 data bits, no parity, and 1 stop bit. A comma-sepa-
rated-value protocol is used by the external controller to make
requests, and by the sampler to report results. Use a standard
computer connect cable (see Appendix E) to connect the sampler’s
interrogator port and the external controller.
For information on serial data codes and their meanings, refer to
Table 5-5 Serial Data Codes in this section.
The 6712 Sampler will respond to three commands: Turn
Sampler On, GET STATUS, and TAKE SAMPLE. All commands
must include the instruction set. The checksum value is optional.
The available commands are:
1. Turn Sampler On: STS,2,CS,582
• “582” is the byte-by-byte sum of the ASCII values in the
string “STS, 1,CS”.
• “” is a carriage return signifying the end of the
command.
• If the sampler is OFF, this command will turn it ON
before returning status info.
2. Get Status: STS,1,CS,581
“STS,1” instructs the sampler to return the current status.
• “CS,581” is the optional checksum value. The
byte-by-byte sum of the ASCII values in the string
“STS,1,CS” is 581.
• “” is a carriage return signifying the end of the
command.
3. Take Sample: BTL,2,SVO,100,CS,1039
The TAKE SAMPLE command is only valid if the sampler is
WAITING TO SAMPLE.
• “BTL,2” instructs the sampler to place the sample in
bottle 2.
• “SVO,100” instructs the sampler to take a 100 ml
sample.