5.3
Writing a Parameter (WRITE)
Writing a parameter is carried out via the fieldbus interface in a similar way to reading a parameter.
A
Write Request from the automation equipment informs the MOVITRAC
®
31.. frequency inverter of
the parameter index to be written, together with the new parameter data. When it receives the write
request, the inverter is instructed to re-define the transferred drive parameter (
Write Indication). The
service is then carried out in the inverter, and if the run is fault-free, the positive response is returned
to the higher-level automation equipment (
Write Response). The Write service is ended on receipt of
confirmation of the service (
Write Confirmation) by the automation equipment.
If it is impossible to carry out the write service in the inverter, e.g. if false parameter data have been
passed over, this is reported back to the automation equipment by a negative answer (
Negative Write
Response). The automation equipment thus receives a negative confirmation (Write Error
Confirmation) with a detailed breakdown of the error.
5.4
Instructions to the User when Adjusting Parameters
When adjusting the parameters of the MOVITRAC
®
31.. frequency inverter via the fieldbus system,
all drive parameters can generally be accessed. However, since some of the drive parameters relate
directly to communication via the fieldbus system, users should take note of the following instructions
when adjusting parameters.
MO
VI
TR
AC
®
841
E
Q
RUN
BUS
FAULT
Master
Slave
Write (1025; 2.5 s)
FIELDBUS
CONTROL MODE
2a. Parameter index 25
(1025-1000) is set to
2.5 s
Negative
write response
Write response
Error + return code
OR
O.K.
Write error
confirmation
3b. Write service faulty because, e.g., parameter value too large
Write
confirmation
3a. Write service was successfully carried out
Write indication
Write
request
1. Write request (e.g. Write to index 1025 = T11 ramp up a
parameter value of 2.5 s)
2b. An error has occurrend!
No data written
00335AEN
Fig. 28: Writing a parameter
Setting Inverter Parameters
5
48
MOVITRAC
®
31.. Fieldbus Unit Profile
Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: [email protected]
