That worked perfectly, Jeff! Thank you very much.
To summarize for future readers, process the comp
file Jeff wrote like this:
halcompile --install toieee.comp
Then add to the HAL file:
loadrt toieee
addf toieee.0 servo-thread
setp toieee.0.update 1
net low mb2hal.00.00.int toieee.0.in-high
net high mb2hal.00.01.int toieee.0.in-low
net ain-00 motion.analog-in-00 toieee.0.out
This will properly convert analog input registers read from
a LabJack UE9-Pro over Modbus TCP into a floating point
value readable by an M66 E0 L0.
Thanks again!
-- Ralph
________________________________________
From: Jeff Epler [jep...@unpythonic.net]
Sent: Friday, December 04, 2015 2:46 PM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] mb2hal and floating point conversions
No existing component will take a 32-bit floating point number encoded
as 2 16-bit "s32" values and output it as a HAL float.
I wrote and gave a very small amount of testing to a component that does.
component toieee
"""Interpret two 16-bit integers or one 32-bit integer as a 32-bit IEEE
floating-point value""";
pin in s32 in-low "Low 16 bits OR full 32-bit floating point value";
pin in s32 in-high "High 16 bits OR zero";
pin in bit update "TRUE to update output, FALSE to hold current value";
pin out float out "Result of conversion";
license "GPL";
function _
"""If update is TRUE, compute a new output value from the input values."""
;
;;
FUNCTION(_) {
if(!update) return;
union { uint32_t i; float f; } u;
u.i = ((uint32_t) in_low) | (((uint32_t) in_high) << 16);
out = u.f; // (automatically promoted from 32-bit float to 64-bit double)
}
For instance, treating the hex value 3EAAAAAB as a 32-bit IEEE float, it
obtains a value close to 1/3:
halcmd: setp toieee.0.update 1
halcmd: setp toieee.0.in-high 0x3eaa
halcmd: setp toieee.0.in-low 0xaaab
halcmd: getp toieee.0.out
0.3333333
However, if this is considered a "standard enough" modbus encoding then perhaps
this decoding should be added directly into mb2hal.
Jeff
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