User guide

SERIAL RS485 COMUNICATION
PAGE 30 AMIS-DMA1 INSTALLATION & OPERATION MANUAL
9.2 Serial port communication parameters (confi g.txt)
The parameters of the RS485 serial port (length of the packets, parity, speed,
etc.) are set in the confi guration fi le confi g.txt.
These parameters must be compatible with the external control system to
which DMA1 is connected.
IMPORTANT!
To make changes to the communication parameters active, it is
necessary to power-cycle the DMA1 after having inserting a fl ash
memory card with the updated confi g.txt fi le.
IMPORTANT! notes for the control system
The DMA1 is ready for serial communication instructions under the
following conditions:
• When DMA1 is turned on
• When the previous communication instruction has been
completed
• When the timeout time for the last received/transmitted packet
has expired
MNEMONIC DESCRIPTION
CMAD
DMA1 address in the RS485 bus (ADD) (Value between 0 and 31 in decimal). IMPORTANT! This address MUST
be unique; two devices with the same address can not co-exist on the same bus.
CMCK Enabling of Checksum:
0=Checksum deactivated
1=Checksum activated
CMCL Enabling inclusion of end-of-packet characters CR and LF (hexadecimal values OD and 0A)
0=No CR and LF
1=Insertion of CR and LF active
CMBR Baud rate (communication speed in bits per second)
0=1200 bps
1=2400 bps
2=4800 bps
3=9600 bps
CMPR Parity Bits:
0=no parity
1=odd parity
2=even parity
CMSB Number of Stop Bits
1=1 StopBit
2=2 StopBits
CMDB Number of data bits
7=7 bits per datum
8=8 bits per datum
CMDR Minimum delay between end of reception a packet and delivery of the reply.
(Value expressed in tens of 1msec between 0 and 15 in decimal)
0=Minimum delay of 4msec
1=Minimum delay of 10msec
2=Minimum delay of 20msec
The following table lists the values and parameters needed to connect the DMA1 to a control system (protocol, speed, timings, etc.).