Serial Communication
Spirit200a User’s Manual Rev J
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6-2
To send a parameter, the parameter value needs to be sent as part of the
command. For example, to send a desired cutting pierce time of 1000
milliseconds to the system, look up the Set Cutting Pierce Time command in the
command table. You will see the following table entry:
Command
# Hex String
Additional Information
Set Pierce Time
4 AA nn FA 04 -- -- 0D
Time in mS (seconds / 1000)
Valid range: 0 to 5000
Once again, AA hex signifies the start of the command, “nn” is the net node of
the power supply, and FA hex is the Spirit identifier. The value 04 hex signifies
the Set Pierce Time command, and 0D hex signifies the end of the command.
The “-- --” in the hex string is the MSB followed by the LSB of a type
int
. The
integer is the value used in the additional information column. Thus, the “-- --” is
sometimes referred to as the additional information value. In the example, we
wanted to transmit a pierce time of 1000 mS (1 second). This value in
hexadecimal would be 03E8 (msb=03, lsb=E8). In this example, the following
string would be transmitted in order to set the pierce time to 1000mS for a power
supply on net node 1:
AA 01 FA 04 03 E8 0D
For multiple power supply installations, commands can be sent to all power
supplies at the same time. This is referred to as a global command. To send a
global command, set the net node value to C8 hex (200 decimal). In the
example above, the following string would be transmitted to set the pierce time to
1000mS for all power supplies connected on the network:
AA C8 FA 04 03 E8 0D
Communication Error Checking
With a single torch system, all commands and parameters transmitted to the
Spirit will be back transmitted in exactly the same form for error checking. With a
multiple torch system, only the system with node focus will back transmit the
commands. The purpose of the node focus command (#254) is to allow one
Spirit system to use the transmission lines at a time. If no node focus is set on
initialization, the first system to receive a command will receive node focus
automatically. Commands may be transmitted to systems without node focus,
but there will be no back transmission from those systems. Also, all parameters
can be read at any time by transmitting a Send Parameter command (#30) to the
Spirit, followed by the appropriate parameter to be read.
