I can't say much without looking at the complete circuit, however the

value

attribute is somewhat wrong. in general you enter text with :

value="text_line_1

text_line_2

text_line_3

...

text_line_n"

Any " character inside the text should be escaped, for example like in:

value="text with embedded \"quotes\", note the backslash characters"

to prevent text double quotes to be interpreted as the closing quote. in your example the value attribute has an opening quote but there is no closing quote after

.endc

and there are unescaped quotes in line

let v_act = "v_act + delta_v"

(I don't think these quotes are needed). My guess is that the correct value setting is: [edit: added backslashes to quotes after the

while

line, not sure if they are needed]

name=s1 only_toplevel=false value=".param start_v=0
.param stop_v=0
.param delta_v=0
.param v_act=0
*tran 10u 400m
.control
let start_v = 0
let stop_v = 0
let delta_v = 0.1
let v_act = start_v
* loop
while \"v(OP)-v(ON)\" le stop_v
alter v8 v_act
tran 10u 400m
write test_offset.raw
print v (start_v)
let v_act = v_act + delta_v
end
.endc"

@Stefan Schippers there are embedded quotes here too, right?

while "v(OP)-v(ON)" le stop_v

@Mitch Bailey Yes, see this short clip. I didn't see the additional quotes, and also I am not sure if they are needed there. If they are needed they should also be escaped.