4-5
4-2 Command and Response Frames
4-2-1 Command Frame
H Transmission Protocol
When receiving a command from the host CPU, the Cam Positioner returns a response frame corre-
sponding to the command. In other words, one response frame is returned in response to one command
frame.
Command and response frames are transmitted as shown in the following illustration.
Host CPU
(personal computer,
PC, etc.)
3F88L-160/162
Cam Positioner
Command frame Command frame
Response frame
H Command Frame Structure
“0” “0” “0” “0” (Refer to 4-3 Command Types.)
STX Node No. Subaddress SID FINS-mini command text (PDU) ETX BCC
No. of bytes 1 2 2 1 1 1
Text
(02
Hex)
(03
Hex)
STX A code signifying the beginning of a communications frame (text). Always
set 02 Hex.
Node No. The node number of a Cam Positioner. Always set “00.”
Subaddress The subaddress of a Cam Positioner. Always set “00.”
SID (service ID) Set the number of retries using a value from “0” to “F.” (See note 1.)
FINS-mini command text Set a service request PDU (protocol data unit). (See note 2.)
ETX A code signifying the end of text. Always set 03 Hex.
BCC
(block check character)
Set BCC as the calculation result of exclusive OR of the data from the node
number to ETX.
Communications Chapter 4
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