Compatibility Modes

Multisim Help

Edition Date: February 2017
Part Number: 375482B-01
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Some other forms of SPICE have slight differences which cannot be automatically detected by Multisim. In order for Multisim to correctly handle these cases it is necessary to add the following special command:

.SYNTAX mode

where mode can be PS for Cadence® PSpice®, XS for XSPICE, and MS for Multisim.

When this command is used, all other elements of the netlist that occur below it (including nested `.subckt` definitions) will be interpreted with special compatibility mode until the end of the current subckt. The default compatibility mode is MULTISIM unless otherwise specified.

Default mode occurs when no .SYNTAX statements are present:

• The mathematical function log is the natural logarithm, except in 'B' arbitrary sources where it is the base 10 logarithm.

MS and XS mode are currently the same:

• The mathematical function log is the base 10 logarithm.
• No absolute value of the base is taken in the mathematical operator **.
• Mathematical expressions do not need to be surrounded by `{}`, however this is still recommended for clarity.

The PS mode has a few differences.

• The mathematical function log is the natural logarithm.
• The mathematical operator `**` is the same as the function PWR, which is equivalent to `abs(x)**y` in Multisim compatibility mode.
• The mathematical operator ^ is xor whereas in Multisim compatibility mode it is another way of writing x**y.
• The step function `STEP(x)` or `STP(x)` or `U(x)` is defined as `if(x>=0,1,0)`.
• Mathematical expressions other than numbers must be surrounded by {}.
• Equal signs are optional between all parameters and their values.
• When the character `*` is not inside {} it marks the start of a comment, even if it is in the middle of a line. Therefore in following example R1 will have a value of 1k in Cadence® PSpice® compatibility mode, but 2k in all other modes.
• R1 1 2 1k*2