Omron S8M - 7-2 Frame Structure

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Frame Structure Section 7-2
Communications
Control Method
Programs are created in the host computer to set or monitor parameters in the
S8M, so the descriptions in this section are from the standpoint of the host
computer.
CompoWay/F is OMRON's unified communications protocol for general-pur-
pose serial communications. This unified format has a proven track record
with OMRON Programmable Controllers, has FINS-compliant commands
(see note), and simplifies communications between the host computer and
components.
Note FINS (Factory Interface Network service) is a messaging protocol for commu-
nications between Controllers in OMRON FA networks.
The S8M has the following communications functions:
• Reading settings and data
• Executing operation commands
• Switching setting levels
The following restriction applies to the communications functions:
• Settings data can be written only when writing is allowed through commu-
nications.
7-2 Frame Structure
7-2-1 Command Frame Structure
STX This code, 02 hex, indicates the beginning of a communica-
tions frame (text). This code must always be set as the first
byte.
When another STX code is received during reception, the
reception starts again from the point where the STX was
received.
Node No.
(Node address)
• The node address identifies the destination node.
• The node address can be set to 00 to 32.
• There will be no response to a transmission with an invalid
node address.
Subaddress The subaddress is not used in the S8M. Always set the subad-
dress to “00.”
SID (Service ID) The SID is not used in the S8M. Always set the SID to “0.”
Command text The command and required text are placed here. Refer to 7-2-
3 FINS-mini Structure for details.
ETX This code, 03 hex, indicates the end of text.
BCC This is the block check character.
The BCC is calculated by taking the exclusive OR of all bytes
from the node number to the ETX.
STX
0 1 0 0 0
ETX
1 2 2 1 1 1
Text
Node No. Subaddress FINS-mini command text
BCC calculation range
BCCSID