Delta Electronics Communication Module RTU-485 - Manual (Page 13)

Modbus Remote I/O Communication Module RTU-485
DVP-PLC Application Manual 11
END
M1129
RST M1129
Process communication time-out
 Explanations
1. You have to set up the communication format at the beginning of the program. The communication
format for the master and slave has to be consistent, e.g. you can see the format is 9600, 7, E, 1,
ASCII from thie example.
2. The master PLC sends out data to RTU-485 in ASCII, e.g. the high byte “30” in D100 refers to “0” and
low bytes “3A” refers to the head code “:”.
3. After M0 is On, set up M1122. At this moment, the master PLC will send the 17 words of data in D100
~ D108 to RTU-485 by RS instruction. The data in low words will be sent first. The master PLC will
store the responding message sent by RTU-485 into D120 ~ D128.
7 LED Indicator & Trouble-shooting
There are four LED indicators on RTU-485, which are POWER, RUN, ALARM and RS-485, for displaying the
working status and communication connection status of RTU-485.
7.1 POWER LED
LED status Indication How to correct
Off No power, or the power is abnormal.
Check the power of RTU-485 and see if the
connection is normal.
Green light On The power of RTU-485 is normal. --
7.2 RUN LED
LED status Indication How to correct
Off RTU-485 is in STOP status. --
Green light On RTU-485 is in RUN status. --
7.3 ALARM LED
LED status Indication How to correct
Off The power is in low voltage. Check if the power of RTU-485 is normal.
Incorrect communication format for
RTU-485 Check if the communication format for RTU-485
is correct.
Incorrect communication address for
RTU-485 Check if the communication address of RTU-485
is valid.
RTU-485 is not connected to
extension module. Check if RTU-485 is connected to extension
module normally.
More than 8 extension modules
connected to RTU-485.
Check and make sure that the number of
extension modules connected to RTU-485 is
less than 8.
Red light On
The number of points on Slim DI/DO
connected to RTU-485 exceeds the
range. Check and make sure the number of input points
on Slim DI/DO connected to RTU-485 is less
than 128, and output points also less than 128.