Cutler-Hammer D320 PLC, Руководство пользователя

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Appendix A: D320 PLC Communication Protocol
209
Read Bits and Words
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Reads the bits and/or word contents of the specified absolute addresses.
•
Can read bits and words regardless of their order and location in memory.
Query (Q) Frame
Response (R) Frame
Methods of assigning bit/word abs. address
0 0 Bit Address
0 1 Word Address
1 x Not Used
Ax = A0, A1,…, An Dx = D0, D1,…, Dn
Assigning absolute address for bits
Abs. address for the K127 12th bit = $1BFC
Ax = 0001 1011 1111 1100
Ax L = $FC, H = $1B
Assigning absolute address for word
Abs. address for the K127 word = $01BF
Ax = 0100 0001 1011 1111
Ax L = $BF, H = $41
Absolute Address
15 14 13 0
DA SA $05 L L H L H … L H L H
AO A1 AN CRC
DA SA $85 Lx DO L H … L H L H
For the A0, A1,…, An requested by the Q, the content D0, D1,…, Dn of
the word/bit is returned.
If Ax denotes a bit address, the Dx data is 1 byte (On = $FF, Off = $00),
and if Ax denotes a word address, the Dx data is 1 word (2 bytes).
The size and location of the
returned data depends on the
combination of bit/word
addresses requested. The Lx
parameter should be checked to
verify data size.
D1 Dn CRC