52
COMMUNICATION PROCEDURE (other than NCP20)
:
Communication Control Signals (DTR Output to DSR Input)
MLM26*RTZ002F
3.2
Communication Control Signals (DTR Output to DSR Input)
The communication control method when the Com mode parameter is set to “NIDEK” or “NIDEK2” is
described.
To transmit and received “Command” and/or “Data”, it is necessary to connect the DSR (Data Set
Ready) and DTR (Data Terminal Ready) wires as well as the TXD (Transmit eXchange Data) and
RXD (Received eXchange Data) wires. (Also see "2.1.2. Cable connection (Page 6)".
The DTR-to-DSR wire allows both devices to know if the other device is ready for communication. If
one device is ready for communication, it sends “DTR = ON” to the other device. If one device is not
ready for communication during printout by the LM or the processing of the previous data by the com-
puter, it sends “DTR = OFF” to the other device to allows the other device to know the status of one
device.
The status of the other device is judged by ON or OFF of “DSR”. In this way, undesired communica-
tion troubles can be prevented.
The figure below shows the changes in the DTR signals when the computer sends “SD command”
and the LM sends “Data” back in response to the command.
1) Both the computer and LM are “out of communication”. The DTR signal of both devices is
“OFF”.
2) The computer enables DTR (ON) to send “Command” to the LM.
TXD
DTR ON
OFF
DTR ON
OFF
TXD
T1 T2
1)
2)
3)
4)
6)
5)
7)
8)
9)
11)
10)
Command
Data
Computer
LM
Com mode “NIDEK”: T1, T2
≤
0.1 second
(Set so that a timeout occurs when T1, T2 > 0.1 second.)
Com mode “NIDEK2”: T1
≤
4 seconds, T2
≤
0.1 second
(Set so that a timeout occurs when T1 > 4 seconds, T2 > 0.1 second
Содержание LM-1800P
Страница 1: ...INTERFACE MANUAL MLM26 RTZ002F LM 1800P LM 1800PD AUTO LENSMETER...
Страница 6: ...2 OUTLINE OF COMMUNICATION Outline of Communication Function MLM26 RTZ002F...
Страница 54: ...50 RS 232C Communication and USB Communication Example of Data Output MLM26 RTZ002F...
Страница 70: ...66 COMMUNICATION PROCEDURE other than NCP20 Flowchart MLM26 RTZ002F...