Reference Manual

PMAC 2 Software Reference

PMAC I-Variable Specification 19

PMAC I-VARIABLE SPECIFICATION

On PMAC, I-variables (Initialization, or Set-up, Variables) determine the “personality” of the

controller for a given application. They are at fixed locations in memory and have pre-defined

meanings. Most are integer values, and their range varies depending on the particular variable.

There are 1024 I- variables, from I0 to I1023, and they are organized as follows:

I-Variable Function

I0 – I99 General card setup (global)

I100 – I186 Motor #1 setup

I187 – I199 Coordinate System 1 setup

I200 – I286 Motor #2 setup

I287 – I299 Coordinate System 2 setup

…

I800 – I886 Motor #8 setup

I887 – I899 Coordinate System 8 setup

I900 – I999 Hardware Channel setup

I1000 – I1023 MACRO and reserved

Global I-Variables

I0 Serial Addressing Card Number {PMAC(1) w/Flex CPU, PMAC2 only}

Range

$0 to $F (0 to 15)

Units

none

Default

Remarks

I0 controls the card number for software addressing purposes on a multi-drop serial

communications cable for all PMAC2 boards and for PMAC(1) boards with an Option 5xF

“Flex” CPU. (On other PMAC(1) boards, the card number is determined by the settings of

jumpers E40 – E43.)

If I2 is set to 2, the PMAC must be addressed with the @n command, where n matches the

value of I0 on the board, before it will respond. If the PMAC receives the @n command,

where n does not match I0 on the board, it will stop responding to commands on the serial

port. No two boards on the same serial cable may have the same value of I0.

If the @@ command is sent over the serial port, all boards on the cable will respond to

action commands. However, only the board with I0 set to 0 will respond to the host with

handshake characters and/or data responses. All boards on the cable will respond to

control-character action commands such as <CTRL-R>, regardless of the current

addressing.

Note:

RS-422 serial interfaces must be used on all PMAC boards for

multi-drop serial communications; this will not work with RS-232

interfaces. If the RS-422 interface is not present as a standard

feature on the PMAC board, the Option 9L serial converter module

must be purchased. It is possible to use an RS-232 interface on the

host computer, connected to the RS-422 ports on the PMAC2

boards.