Chapter 2
2-2
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 Description
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.
STX
1
2
Node number
Sub-address
SID
Tex t
BCC calculation range
BC
Command text
21 11
ETX
000
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