Data Format; Command Frame - Omron EasySpeed 3G3JV Series Communications Manual

CompoWay/F Communications Procedures
2-1

Data Format

This section describes the procedures for communications according to the CompoWay/F protocol.
• Hexadecimal values are expressed by adding the prefix H' before the number, e.g., H'02.
• Numbers shown without the H' prefix are ASCII characters. (For a table of ASCII codes, refer to the
appendix.)
• The number underneath each item in a frame indicates the number of bytes.

Command Frame

Name
STX • This code (H'02) indicates the beginning of the communications frame (text).
• Always set this character in the first byte.
• If STX is received again during reception, reception is carried out again from the point
where STX was received.
Node number • This number specifies the transmission's destination.
• Specify the 3G3JE's communications unit number.
• A BCD value between 00 and 99 or ASCII "XX" can be set.
• Specify "XX" for a broadcast transmission. No responses will be returned for broadcast
transmissions.
• No responses will be returned from node numbers other than the ones in the above
range.
Sub-address • The sub-address is not used with the 3G3JE.
• Always set the sub-address to "00."
SID • This is the service ID.
• The service ID is not used with the 3G3JE.
• Always set the service ID to "0."
Command text This is the command text area. For details, refer to 2-2 Structure of Command Text.
ETX This code (H'03) indicates the end of the text.
BCC • This is the Block Check Character.
• The BCC result is found by calculating the exclusive OR of all bytes from the node num-
ber through ETX.
2-2
Node number Sub-address SID
STX 0 0
1
2 2
BCC calculation range
Text
Command text
0
ETX
1
Description
Chapter 2
BCC
1 1