4-2
IM 77C01H01-10EN
4.1 Overview
4.1.1
Configuration of Command
Commands sent from a higher-level device to the UPM100 consist of the following elements.
Number
of
Bytes
1
2
2
1
3
Variable
length
2
1
1
Element
STX
Station
number
(ST-NO)
CPU
number
(01)
Time to
wait for
response
(0)
Command
Data
corresponding
to command
Checksum
ETX
CR
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
1. STX (Start of Text)
This control code indicates the start of a command. The ASCII code is 02 in
hexadecimal.
2. Station Number (01 to 99)
Station numbers are used by the higher-level device to identify the UPM100 at the
communication destination. (These numbers are identification numbers specific to
individual UPM100.) P1: Broadcasting mode
3. CPU number
This number is fixed to “01”. The ASCII codes are 30 and 31 in hexadecimal.
4. Time to Wait for Response
This is fixed to “0”. The ASCII code is 30 in hexadecimal.
5. Command (See section 4.2, “Command and Response”)
Specify a command to be issued from the higher-level device.
6. Data Corresponding to Command
Specify an internal register (D register or I relay), number of data pieces, and others.
7. Checksum
This is required if the protocol with checksum is selected for the RS-485 communication
protocol parameter “COMM.”
It converts the ASCII codes of texts between the character next to STX and the
character immediately before the checksum into hexadecimal values and adds them
byte by byte. It then fetches the single lowermost byte of the added results as the
checksum.
This column is required only for PC link communication with checksum. PC link
communication without checksum does not require this 2-byte space of ASCII code.
[Example]
[STX]01010BRDI0001, 001[ ][ ] [ETX][CR]
Add up the hexadecimal values of the ASCII codes of each text.
(“0” : 30, “1” : 31, “B” : 42, “R” : 52, “D” : 44, “I” : 49, “,” : 2C)
30+31+30+31+30+42+52+44+49+30+30+30+31+2C+30+30+31=391
Lowermost two digits of the added results as the checksum.
[STX]01010BRDI0001,00191[ETX][CR]
8. ETX (End of Text)
This control code indicates the end of a command string. The ASCII code is “03” in
hexadecimal.
9. CR (Carriage Return)
This control code indicates the end of a command. The ASCII code is “0D” in
hexadecimal.
Note
The control codes “STX”, “ETX”, and “CR” are essential for commands when you create a
communication program for PC link communication. Omission of any of them or incorrect order of
them results in communication failure.
Summary of Contents for UPM100
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