Pixsys DRR244 - Serial Communication

20 - DRR244 - User manual
8 Serial communication
DRR244-13ABC-T is equipped with RS485 and can receive/broadcast data via serial communication
using MODBUS RTU protocol. The device can only be configured as a Slave. This function enables the
control of multiple controllers connected to a supervisory system / SCADA.
Each controller responds to a Master query only if the query contains the same address as parameter
318
sL. a d . ( “Slave Address” ).
The addresses permitted range from 1 to 254 and there must not be controllers with the same address
on the same line.
Address 255 can be used by the Master to communicate with all the connected equipment (broadcast
mode), while with 0 all the devices receive the command, but no response is expected.
The baud rate is selected on parameter 319
bd . rt. ( “Baud Rate” ).
DRR244 can introduce a delay (in milliseconds) of the response to the master request. This delay must
be set on parameter 321
se. d e. ( “Serial Delay” ).
Each parameter modification is saved by the controller in the EEPROM memory (100000 writing cycles),
while the setpoints are saved with a delay of 10 seconds after the last modification.
Changes made to words that are different from those reported in the following table can lead to
malfunction.
Modbus RTU protocol features
Baud-rate
Selectable on parameter 319
bd . rt.
1200bit/s 28800bit/s
2400bit/s 38400bit/s
4800bit/s 57600bit/s
9600bit/s 115200bit/s
19200bit/s
Format
Selectable on parameter 320
s. p. p.
8N1 8N2
8E1 8E2
8O1 8O2
Supported
functions
WORD READING (max 50 word) (0x03, 0x04)
SINGLE WORD WRITING (0x06)
MULTIPLE WORDS WRITING (max 50 word) (0x10)
Here below a list of all available addresses and supported functions:
RO = Read Only R/W = Read/Write WO = Write Only
Modbus
address
Description
Read
Write
Reset
value
0 Device type RO 474
1 Software version RO Flash
2 Boot version RO Flash
3 Slave Address RO Eepr/dip
6 Baud rate RO Eepr/dip
50 Slave address automatic learning WO -
51 System code comparison for slave address automatic learning WO -
500 Loading default values (write 9999) RW 0
501 Restart DRR244 (write 9999) RW 0
502 Setpoint storing delay time RW 10
503 Parameters storing delay time RW 1
701 First character of the custom alarm message 1 RW “u“
...
723 Last character of the custom alarm message 1 RW 0
751 First character of the custom alarm message 2 RW “u“
...