Yaskawa 545 PLC - Manual (Page 9)

4 OPERATION
8 Sending Numerics from PLC to DSD
4/12/94
the module. If this word is displayed, and the points X0001, X0002 and
X0016 are enabled and the rest are disabled, then the value shown is Hex
C001. X0001 is the most significant bit in that word, X0016 the least. The
MicroTrac LAN message for allocating and upgrading logic contains a 4 byte
mask field. If the bits within these 4 bytes are labeled 63-0, with 63 being the
most significant bit and 0 the least significant bit, then to address point X0001
requires bit 1 (not bit 0) to be on, bit 2 for X0002, and so on.
DSD PAC code (PAC – programmable application code – the custom part of
the DSD software) can be written to allow the PLC to send numerics to the
DSD through either of two means. One method simply uses a NUMI block
(numeric input) in the PAC code set to the proper PLC address. The other
allows the PLC to read and change an adjustable function number parameter.
Either method can be applied to any given numeric, and both methods can be
utilized in a single PAC diagram.
The NUMI block method allows the same numeric to be set only from the
PLC. It requires only one PLC address per numeric. The function number
method allows the same numeric to be set from multiple locations, but requires
two PLC addresses and needs additional PLC programming. This method
does not allow the PLC to set the parameter outside of the predefined range of
that number.
Adjustable parameters in the DSD are assigned function numbers between F1
and F299. These settings can be changed by using the standard testmeter
which can be located on the DSD main PCB (SCDU – standard control display
unit), the handheld testmeter (PCDU – portable control display unit), the
remote display (RDU – remote display unit), or one or more of the many video
screen, computer, or PLC connections to the LAN. DSD function number
parameters that are to be settable through the PLC are placed in the “PLC
INITIALIZATION” table that is usually located near the end of the DSD PAC
diagram (software schematic diagram). This table defines the PLC address
and decimal location for each parameter.
When the DSD/PLC interface detects a change in data from the PLC, it sends
this new value over the LAN to the appropriate DSD. If this new setting is out
of range for the function number in question, then the DSD/PLC interface
sends the nearest allowed value to the DSD. The DSD then sends the new
value it received back to the PLC as confirmation of a successful update.
When the parameter is changed from a location other than the PLC (for
instance, by using the RDU remote display), the DSD sends the new value to
the PLC and expects the PLC to return this new value as confirmation of this
change.
Sending
Numerics from
PLC to DSD
Function
Number
Method
Specifics
RD 3056-10