ABB ACH550-UH User Manual

ACH550-UH User’s Manual 1-199
Embedded fieldbus
and read. Mailbox can also be used to adjust parameter settings by writing a value to
any parameter identified. The following table describes the use of this function.
1. As noted above, Modbus provides direct access to all parameters using the format: 4 followed by
the parameter number.
Actual value scaling
The scaling of actual values can be protocol dependent. In general, for Actual
Values, scale the feedback integer using the parameter’s resolution. (See Complete
parameter descriptions section for parameter resolutions.) For example:
Where parameters are in percent, the Complete parameter descriptions section
specifies what parameter corresponds to 100%. In such cases, to convert from
percent to engineering units, multiply by the value of the parameter that defines
100% and divide by 100%. For example:
1. Assuming, for the sake of this example, that the Actual Value uses parameter 9908 MOT NOM SPEED
as the 100% reference, and that 9908 = 1500 rpm.
2. Assuming, for the sake of this example, that the Actual Value uses parameter 9907
MOT NOM FREQ
as the 100% reference, and that 9907 = 500 Hz.
Although Actual Value scaling could differ from the above for the N2 and FLN
protocols, it currently does not. To confirm, see the following sections, as
appropriate:
• N2 analog input objects in the N2 protocol technical data section.
• Scaling drive feedback values in the FLN protocol technical data section.
Scaling does not apply for the BACnet protocol.
Name Description
Protocol Reference
Modbus
1
N2 FLN BACnet
Mailbox
Parameter
Enter the number of the drive parameter
to access.
Does not
apply.
AO19 95 AV25
Mailbox
Data
Contains the parameter value after a
read, or enter the desired parameter
value for a write.
AO20 96 AV26
Mailbox
Read
A binary value triggers a read – the value
of the “Mailbox Parameter” appears in
“Mailbox data”.
BO19 97 BV15
Mailbox
Write
A binary value triggers a write – the drive
value for the “Mailbox Parameter”
changes to the value in “Mailbox data”.
BO20 98 BV16
Feedback
Integer
Parameter
Resolution
(Feedback Integer) * (Parameter Resolution) = Scaled Value
1 0.1 mA 1 * 0.1 mA = 0.1 mA
10 0.1% 10 * 0.1% = 1%
Feedback
Integer
Parameter
Resolution
Value of the
Parameter that
defines 100%
(Feedback Integer) * (Parameter Resolution) *
(Value of 100% Ref.) / 100% = Scaled Value
10 0.1% 1500 rpm
1
10 * 0.1% * 1500 RPM / 100% = 15 rpm
100 0.1% 500 Hz
2
100 * 0.1% * 500 Hz / 100% = 50 Hz

ABB ACH550-UH Specifications

General

Brand	ABB
Model	ACH550-UH
Category	Controller
Language	English