IBM Car Amplifier 7220 Manual de usuario descargar pdf (Pagina 55)

5-15

Chapter 5, FRONT PANEL OPERATION

5.2.10 GPIB Setup 2 Menu

Figure 5-11, GPIB Setup 2 Menu

This menu, shown in figure 5-11, has two controls affecting the GPIB computer

interface, as follows:-

SRQ Mask

The instrument includes the ability to generate a Service Request on the GPIB

interface, to signal to the controlling computer that urgent attention is required. The

request is generated when the result of a logical bit-wise AND operation between the

Service Request Mask byte, set by this control, and the instrument’s Status Byte, is

non-zero. The bit assignments of the Status Byte are as follows:-

Bit Decimal value Function

0 1 command complete

1 2 invalid command

2 4 command parameter error

3 8 reference unlock

4 16 overload

5 32 auto-mode active or new ADC values available after

external trigger

6 64 asserted SRQ

7 128 data available

Hence, for example, if the SRQ mask byte is set to decimal 16 (i.e. bit 4 is asserted),

a service request would be generated as soon as an overload occurred; if the SRQ

mask byte were set to 0 (i.e. no bits asserted), then service requests would never be

generated.

Test echo

When this control is enabled, all transmissions to and from the instrument via the

GPIB interface are echoed to the RS232 interface. Hence if a terminal is connected to

the latter port, it will display any commands sent to the instrument and any responses

generated, which can be useful during program development. When disabled, echoing

does not occur. The control should always be disabled when not using this feature,

since it slows down communications.

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IBM Car Amplifier 7220 Manual de usuario Pagina 55