Husky MP2500 Manual page 154

Setting
Yes
No Extra LFs will not be inserted, although any LFs in the
Note: When sending binary data (such as a machine code program), set
LF to No to avoid corrupting the data.
Also note that with LF on, you are adding characters to the transmitted data,
so the length will be greater and mechanisms such as checksums will be
misled.
NULL
Use
To control whether the MP2500 inserts NULL characters (decimal 0,
hexadecimal 00H) after each CR, when transmitting.
Notes
This option is mainly provided for use with printers that take a significant
time to perform a Carriage Return operation and don't have handshaking or
buffering. NULLs are not printed, they simply give the printer time to
perform the CR function.
Setting
0
1..20
If LF is set to 'y', any NULLs will be sent after the CR LF sequence.
Note: If transmitting binary files, set NULL to 0 to avoid corrupting the
data.
132
Result
A LF will be inserted after each CR transmitted, even if
there is already a LF in the text.
data will be transmitted as normal.
Result
No NULLs are added.
1..20 NULLs are added.
H MP2500 System Developer's Guide
USKY