Flintec LDU 78.1 - Manual (Page 27)

LDU 78.1 Technical Manual, Rev. 12 May 2011 Page 27 of 36
8.10. Communication Setup Commands – AD, BR, DX, TD, OP, CL
8.10.1. AD Device Address
This command can set up the device address in the value range from 0 to 255.
Master (PC / SPS) sends Slave (LDU XX.X) responds Meaning
AD  A:000 Request: Address 0 (= factory default)
AD 49
 OK Setup: Address 49
Setting the device address to “0“ will cause the device to be permanently active, listening and responding to
every command on the bus without the need for an OP command.
Note: After editing the address you first have to save the changes (command WP) and then restart the device.
8.10.2. BR Baud Rate
With this command the following baud rates can be setup: 9 600, 19 200, 38 400, 57 600 and 115 200 Baud.
Master (PC / SPS) sends Slave (LDU XX.X) responds Meaning
BR  B 9600 Request: 9 600 Baud (= factory default)
BR 115200
 OK Setup: 115 200 Baud
In chapter 4.3 an automatic search and adjusting mode for the baud rate is described.
Note: After editing the baud rate you first have to save the changes (command WP) and then restart the
device.
8.10.3. DX Half-duplex or Full-duplex
With this command the serial communication can be set to half-duplex (DX=0) or full-duplex (DX=1).
Master (PC / SPS) sends Slave (LDU XX.X) responds Meaning
DX  X:000 Request: DX = 0 (Half-duplex, factory default))
DX 1
 OK Setup: DX = 1 (Full-duplex)
Half duplex communication can be used for 2 wire RS485 communication.
Attention: The auto transmit commands SG, SF, SW and SL will only work if full duplex communication
(DX=1) is selected.
8.10.4. TD Transmission Delay
This command allows time delays from 0 to 255ms before any response from the LDU. This delay may be
necessary in some two wire applications.
Master (PC / SPS) sends Slave (LDU XX.X) responds Meaning
TD
 T
0 Request: TD = 0 ms (factory default)
TD 20  OK Setup: TD = 20 ms
8.10.5. OP Open Device
Master (PC / SPS) sends Slave (LDU XX.X) responds Meaning
OP
 O:00003 Request: Device #3 is open
OP 14  OK Open device #14
This command, if sent without parameters, requests the address or device number of the device active on the
bus. If sent with parameters, this enables the device defined by the parameters.
The requested device acknowledges its readiness and responds to all bus commands until a further OP
command arrives with a different device address or a CL command is received.
All LDUs operate with an improved communication protocoll:
Each OP command implies a CL command for all non-addressed devices. This simplifies the addressing and
increases the performance within the bus system.
8.10.6. CL Close Device Address n
Master (PC / SPS) sends Slave (LDU XX.X) responds Meaning
CL 3  OK Close device #3
CL  OK Close all connected devices