TOHO ELECTRONICS TTM-00BT - Manual (Page 20)

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7.9.5 Composition of a request message (transmitted from a high-level computer to
this product)
n For codes ① to ⑧, see "7.9.9 Code description."
n For specific examples of request messages, see "7.9.11 Examples of communications to be
read" and "7.9.12 Examples of communications to be written."
1) Composition of a read request message
S
T
X
□ □ R □ □ □
E
T
X B
C
C
① ② ③ ④ ―⑤― ⑦ ⑧
Start code Unit number Channel Contents of the request: read Identifier End code BCC data
2) Composition of a write request message
S
T
X
□ □ W □ □ □ □ □ □ □ □
E
T
X B
C
C
① ② ③ ④ ―⑤― ―――⑥――― ⑦ ⑧
Start code Unit number Cha
nnel
Contents of the request: write Identifier Numerical data End code BCC data
3) Composition of a store request message
S
T
X
□ □ W S T R
E
T
X B
C
C
① ② ③ ④ ―⑤― ⑦ ⑧
Start code Unit number Channel Contents of the request: write Identifier E
nd code
BCC data