Measurement Computing GPIB-488.2 - Manual (Page 6)

1-4 Introduction 978492 GPIB 488.2 Porting Guide
How to Use the Guide
Before beginning any API conversions, you will need, in addition to this guide, the following:
o
Your API code
o
IOtech’s Personal488 User’s Manual (495-0903)
o MCC’s GPIB-488 Programming Reference Manual (371930C-01)
Both documents are available, in PDF format, from the IOtech website.
To make the conversions:
1) From your API routine, identify your current IOtech commands; for example,
CheckListener
2) From chapter 2 of this porting guide, find the associated MCC commands; for
example, FindLstn
3) From GPIB-488 Programming Reference Manual, look up the detailed information,
i.e., Syntax, Parameters, Returns, Usage Notes, and Examples.
4) Substitute the IOtech routines with MCC routines.
Terms
The following term definitions were obtained from the MCC document, GPIB-488
Programming Reference Manual, p/n 371930C-01.
GPIB - General Purpose Interface Bus
System controller - The system controller has the unique ability to retrieve active control of
the bus or to enable devices to be remotely programmed. It takes control of the bus by issuing
an IFC (Interface Clear) message for at least 200 µsec. It also can put devices into the remote
state by asserting the REN (Remote Enable) line.
There is always one system controller in a GPIB system. The system controller is designated at
system initialization either through the use of hardware switches or by some type of
configuration software, and is not changed. The system controller can be the same controller as
the one which is the current active controller or an entirely different one. Note that if a
controller is both a system controller and the active controller and it passes control to another
controller, the system controller capability is not passed along with it.
Active controller - The active controller is the controller which has the ability to mediate all
communications which occur over the bus. In other words, the active controller designates
(addresses) which device is to talk and which devices are to listen. The active controller is also
capable of relinquishing its position as active controller and designating another controller to
become the active controller.
Device - A device is any IEEE-488 instrument which is not a system controller or active
controller. It can be idle or act as a talker and/or listener when addressed or unaddressed by the
active controller.