Interface Signal; Meaning Of Interface Signal; Rs-232C Interface Signal Level And Meaning - Hitachi 902 Service Manual

16.9.3 Interface Signal

Table 16-27 lists the meanings of interface signals, and Tables 16-28 and 16-29 list signal
levels and their meanings.
Abbreviation
FG Frame Ground
TXD Trans Data
RXD Receive Data
RTS Request To Send
CTS Clear To Send
SG Signal Ground
Table 16-28 RS-232C Interface Signal Level and Meaning
Signal Level
Signal Name
TXD
RXD
RTS
DTS
CTS
NOTES: 1. Positive
Negative
2. Data "0" and data "1" correspond to decimal numbers for the CPU to read/write data or
status, respectively.
Table 16-27 Meaning of Interface Signal
Signal Name
Frame ground
Transmission data
Reception data
Request to send
Clear to send
Signal ground
Positive (NOTE 1)
• SPACE
• Start bit
• Data "0" (NOTE 2)
• ON
• Data "1"
• ON
• Data "1"
• Data communication allowed
O utput +12 V, input +3 V to 15 V
..........................
Output -12 V, input -3 V to 15 V
.......................
Meaning of Signal
• MARK (no signal)
• Stop bit
• Data "1" (NOTE 2)
• OFF
• Data "0"
• OFF
• Data "0"
• Data communication prohibited
16 - 47
Direction of Signal
(902 side) (Host side)
→
←
→
←
Negative (NOTE 1)