adccommunitymod (AutomationDirect) asked a question.
Scaling analog input for rpm display
Created Date: September 12,2009
Created By: polishfog
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I have an analog input, 0-10V, reading 0-60Hz (frequency). LD V2002 MUL K1100 DIV K4095 DIV K10 OUT V2102 This works fine, now I want to display the speed of the motor, so I try and scale it for 0-1450rpm; suing the ANSCL instruction. However, it does not seem to work. RAW V2102 HI ENG 1450 LO ENG 0 ENG OUT V3003 How can I make this work? Is there an easy way? Thanks!
Created Date: September 12,2009
Created by: bfitz
The ANSCL is expecting a 0-4095 BCD input. You have it pointing to a register that was scaled to hold 0-60 full scale.
To fix this, you could point the RAW register to V2002 (the register that apparently holds the actual raw input). If a count of 4095 represents a motor speed of more than 1450 rpm (I'm guessing this is the case), then enter whatever the motor speed would be for that count. You would essentially be setting up two different scaled values coming from the same raw input.
Brian
Created Date: September 12,2009
Created by: polishfog
ok, I tried this, however, my displayed value is off.
the actual motor speed is 480 (rpm) and my displayed speed is 520.
there is an offset someplace.
Created Date: September 12,2009
Created by: bfitz
Could you list what you have now for the values in the scaling instruction?
Created Date: September 12,2009
Created by: polishfog
Could you list what you have now for the values in the scaling instruction?
raw data coming in: 1470
engineering value out: 520
Created Date: September 12,2009
Created by: bfitz
Actually, I meant the values in the HI ENG and LOW ENG slots. What I am driving at is an apparent inconsistency in your first post. You say that your first scaling formula scales the 0-10V input to read 0-60 Hz. However, it looks like it is actually setup to scale it from 0-110 Hz. Now, assuming that your motor nameplate lists a speed of 1450 rpm at 60 Hz, the full speed at 110 Hz would be approximately 2660 Hz. If your 0-10V input is in fact scaled 0-110 Hz, you need to use 2660 as the HI ENG value for your speed scaling, not 1450 as you have now.
Brian
Created Date: September 12,2009
Created by: polishfog
Actually, I meant the values in the HI ENG and LOW ENG slots. What I am driving at is an apparent inconsistency in your first post. You say that your first scaling formula scales the 0-10V input to read 0-60 Hz. However, it looks like it is actually setup to scale it from 0-110 Hz. Now, assuming that your motor nameplate lists a speed of 1450 rpm at 60 Hz, the full speed at 110 Hz would be approximately 2660 Hz. If your 0-10V input is in fact scaled 0-110 Hz, you need to use 2660 as the HI ENG value for your speed scaling, not 1450 as you have now.
Brian
I have a drive that is putting out a freq analog signal, this is scaled as in my original post. It does display the correct frequency.
the drive shows:
15 Hz
727 rpm
the ANSCL instruction:
RAW V2102 (30) (Hz)
HI ENG 1450
LO ENG 0
ENG OUT V3003 (786) (rpm)
Created Date: September 12,2009
Created by: polishfog
I changed the HI ENG unit:
drive:
7 Hz
174 rpm
********
ANSCL instruction:
RAW V2102 (7) (Hz)
HI ENG 1339
LO ENG 0
ENG OUT V3003 (171) (rpm)
******************************
drive:
27 Hz
657 rpm
********
ANSCL instruction:
RAW V2102 (27) (Hz)
HI ENG 1339
LO ENG 0
ENG OUT V3003 (658) (rpm)
******************************
drive:
50 Hz
1218 rpm
********
ANSCL instruction:
RAW V2102 (50) (Hz)
HI ENG 1339
LO ENG 0
ENG OUT V3003 (1225) (rpm)
******************************
drive:
60 Hz
1450 rpm
********
ANSCL instruction:
RAW V2102 (54) (Hz)
HI ENG 1339
LO ENG 0
ENG OUT V3003 (1339) (rpm)
******************************
Created Date: September 12,2009
Created by: bfitz
What was the raw reading (V2002) when the drive was reading 60 Hz, 1450 rpm?
Created Date: September 12,2009
Created by: milldrone
I have an analog input, 0-10V, reading 0-60Hz (frequency).
LD V2002
MUL K1100
DIV K4095
DIV K10
OUT V2102
This works fine,
polishfog,
When I put a value of 4095 into V2002 I get "110 " with this. Not "60Hz "
Created Date: September 12,2009
Created by: polishfog
I'm going to have to get back to this on Monday afternoon. I had to leave the plant and I cannot open the file here.