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Turbo PMAC/PMAC2 Software Reference

Turbo PMAC On-line Command Specification 357

See Also:

M-Variables (Computational Features)

On-line commands M{constant}, M{constant}->,

M{constant}->TWD:{address}

Thumbwheel Multiplexer Board (Acc-18) Manual

M{constant}->TWD:{address}

Function: BCD Thumbwheel-Multiplexer M-Variable Definition

Scope: Global

Syntax: M{constant}[..{constant}]->TWD[:]{multiplex address},

{offset},{size}[.{dp}],{format}

where:

 {constant} is an integer from 0 to 8191 representing the number of the M-variable;

 the optional second{constant} must be at least as great as the first {constant} -- it represents

the number of the end of the range;

 {multiplex address} is an integer constant in the range 0 to 255, representing the address in

the multiplexing scheme on the thumbwheel port of the most significant digit (lowest address) to be

used in the M-variables;

 {offset} is 0 or 4, representing whether the most significant digit is in the low nibble (left digit of

pair) or high nibble (right digit of pair) of the pair of digits at {multiplex address},

respectively;

 {size} is an integer constant from 1 to 12, representing the number of digits to be used in the M-

variables;

 {dp} (optional) is an integer constant from 0 to 8, representing the number of these digits to be

interpreted as being to the right of the decimal point;

 {format} (optional) is either U for unsigned, or S for signed. If it is signed, the least significant

bit of the most significant digit is taken as the sign bit (the rest of the most significant digit is

ignored). If no format is specified, U (unsigned) is assumed.

This command causes Turbo PMAC to define the specified M-variable or range of M-variables to point to

a set of binary-coded-decimal digits multiplexed on the thumbwheel port with Accessory 18 or

compatible hardware.

Thumbwheel-multiplexer M-variables are read-only, floating-point variables. Once defined, they are to

be used in expressions, and queried. Each time one is used in an expression, the proper addresses on the

multiplexer boards are read.

Example:

M100->TWD:4,0,8.3,U means the most significant digit is at multiplex address 4, low nibble (left

digit); there are eight digits, three of which are fractional; and it is always interpreted as a positive value.

This corresponds to eight thumbwheel digits along the bottom row of the lowest-addressed thumbwheel

board, with the decimal point three digits in from the right.

M99->TWD:0,0,1,U means that a single digit is used, at multiplex address 0, low nibble (left digit).

This corresponds to the upper left thumbwheel on the lowest-addressed thumbwheel board.