Teledyne 6712FR manual Pressurized Lines Command Driven Operation, Waiting to Sample

6712FR Refrigerated Sampler Section 5 Extended Programming

5.21 Pressurized Lines

5.22Command Driven Operation

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.

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 5-5Serial 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<CR>

•“582” is the byte-by-byte sum of the ASCII values in the string “STS, 1,CS”.

•“<CR>” 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<CR>

“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.

•“<CR>” is a carriage return signifying the end of the command.

3.Take Sample: BTL,2,SVO,100,CS,1039<CR>

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.

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