Read link parameters, Read modifyćwrite (write bit) – Rockwell Automation 1770, D17706.5.16 Ref Mnl DF1 Protocol Command User Manual
Page 107
7–20
Communication Commands
Publication 1770Ć6.5.16 - October 1996
read link parameters
Reads the DH485 parameter, Maximum Solicit Address.
This parameter specifies the maximum node address that a DH485
node tries to solicit onto the link.
CMD
06
STS
FNC
09
TNS
CMD
46 STS
TNS
DST SRC
SRC DST
Data
Address
0000
Size
01
Data - the maximum node address that can be solicited (1 byte).
C
R
read modifyĆwrite (write bit)
Sets or resets specified bits in specified words of data table memory.
The interface that receives this command performs this procedure for
each PLC-5 system address, AND Mask, and OR Mask in the
message packet:
1.
Copies the specified word in the data table.
2.
Resets the bits specified in the AND mask.
3.
Sets the bits specified in the OR mask.
4.
Writes the word back to its location.
The PLCĆ5 system address specifies the word that is modified. Use more than one field to specify more
than one word. Must point to a word, and can be either a logical binary address or a logical ASCII
address.
(Repeatable up to 243 bytes)
CMD
0F
STS
FNC
26
TNS
C
CMD
4F STS
TNS
R
DST SRC
SRC DST
EXT
STS
AND Mask
PLCĆ5 sys. address
OR Mask
The EXT STS field may be attached to the reply packet only when there is an error.
Each PLCĆ5 system address is followed by an AND Mask (specifies which bits in the word to reset [0])
and OR Mask. (specifies which bits in the word to set [1]). These three fields can be repeated up to a
length of 243 bytes.
AND and OR Masks: two bytes each with the low byte first.
•
AND Mask: 0 to reset a bit, 1 to leave it the same.
•
OR Mask: 1 to set a bit, 0 to leave it the same.
Important: The controller may change the states of the original bits
in memory before this command can write the word
back to memory. (Some data bits may unintentionally
be overwritten.) To help prevent this, we suggest that
you use this command to write into the storage area of a
programmable controller’s data table, and have the
controller read the word only, not control it.
•
SLC 500
•
SLC 5/03
•
SLC 5/04
(Channel 0
configured for
DH485)
•
PLCĆ5
•
PLCĆ5/VME