User`s guide

Installation and Setup

The Fail signal can be generated at a number of points in the

sequence, including detection of an empty tube position or an error

condition. Closure of the Fail contacts is always associated with an

error message or a fatal error message.

ATD/TD Input Signals

Ready In—The ATD/TD can determine the status of external

instrumentation using the Ready In signal. A relay contact closure,

or equivalent, from the external device, connected between pin 9

(Ready In) and Ground (pins 12, 13 or 14), indicates to the ATD/TD

that the GC is ready to receive a sample. See Figure 1.

The ATD/TD examines the status of the external device several

times during a sequence including before a sample tube is loaded,

before the tube is purged, and before trap is heated. If a GC Ready

signal is not received at these times, the ATD/TD status messages

“Ready To Load,” “Ready For Desorb,” or “Ready To Inject” appear

and the ATD/TD waits until the GC Ready signal is received.

To obtain overlapping tube desorption, a non-zero GC Cycle Time

can be set. In this case, on the second and subsequent desorption

cycles the GC ready signal is examined only before trap heating.

To disable the ATD/TD from monitoring the external ready signal,

pins 9 and 12, 13, or 14 should be shorted together with a small

length of wire. (Useful for “stand alone” or service operation.)

Start In and Stop In—The inputs are handshake signals, that are

currently not used by the instrument.

RS-232C Port—This 9 pin port has programmable baud rate, and is

intended for computer communications. It can be configured through

the Preferences tab. See Preferences Tab on page 117. Refer to the

ATD/TD Control Software manual for details on connecting your

computer to the ATD/TD.

BCD—The number of the tube in the analysis position (the rear-

most position on the carousel) is available in BCD form. Each digit

is signaled by relay contact closures between the BCD appropriate

pins and Common Out. See BCD Interface on page 185.

NOTE: The options board is required in order to obtain BCD

signals.