Control Techniques UD70, User Manual

Page: 135 / 154

UD70
Issue code: 70nu2
Features 8-37
8.14 Non-volatile memory storage
The
UD70
has a feature which allows it to store the P and Q regions of the
PLC
register-set into the non-volatile memory of the
UD70
. This can be
initiated by setting parameter #17.19 at 1.
This parameter immediately returns to zero once it has been set. Also, the
UD70
is reset when the parameter is set. This re-starts the user program.
This feature can be used to store information such as the value of the
diameter of a winder, or run-time counters, or any program variables. Also,
when using the in-built position controller, all the setup parameters (prefix
_ Q) and position registers can be saved. The
UD70
automatically restores all
the registers when
AC
power is restored.
8.15 Using the RS232 port for
Drive-to-Drive communications
The
MD29
card and
UD70
module have a mode in which the
RS232
port can be
linked to another
MD29
or
UD70
and two 32-bit variables can be transmitted
between them.
The
RS232
port can be used for Drive-to-Drive communications when the
RS485
port is being used by another device (a user-interface (
MMI
), for
example). The protocol used employs CRC checking to ensure a high
degree of data integrity.
Warning
Due to the inferior specification of
RS232
, the serial
communications cable connecting the Drives must be as
short as possible (less than 10 metres (30 feet)). RS232–
RS485 converters can be used to extend the cable length
if required.
Note that serial communications multi-drop is not
possible. The
RS232
Drive-to-Drive link is designed solely
for connecting to one external
MD29
card or
UD70
module.
No handshaking is performed on this link (ie. no error
will reported if the connection is broken, for example).