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(3) Station number switch (STA NO.)
Make sure to set the master station number to "00." For slave stations, set from "01" to "77" in
octagonal sequence.
- Maximum amount of slave stations to be connected are
63. As the station number should be assigned by
octagonal figures, setting of the following values causes
errors and the JW-21MN cannot communicate.
08, 09, 18, 19, 28, 29, 38, 39, 48, 49, 58, 59, 68, 69, and
78 to 99.
- Be careful that there is no doubly allocated number and no
number has been skipped.
(4) Termination resistance switch (LT)
When the JW-21MN is at the termination station of the communication line, make sure to set the
termination resistance switch to "ON."
Turn ON the termination resistance switches
for these two stations.
Setting
ON
Insert a termination resistance
OFF
Do not insert a termination resistance
- When using a termination (ME-75 made by Toko
Denshi) (device to function as terminator) at the end
of a signal cable, turn "OFF" the termination resis-
tance switch of the termination station.
Termination
Reference
Need for the termination resistance
When a termination resistance is not provided at a communication circuit end, the end of the circuit
generates reflection waves. These reflection waves collide with sending signals and abnormal
communication may occur. The termination resistance prevents the occurrence of these reflection
waves. On the other hand, when an intermediate station has its termination resistance switch turned
"ON," this station causes reflection and attenuates signals and causes abnormal communication.
STA NO.
(Factory setting: 00)
Condition of the JW-21MN
1 km max.
Termination
(ME-75)
11-3
STA NO.
×10
× 1
ON
LT
OFF
(Factory setting: OFF)
Termination
(Front side)
11
4
C
(Rear side)
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