MODELS 483C30, 483C50, 482M179 AND 483M217 GENERAL OPERATION MANUAL
16
Command type definitions;
•
R/W – the setting can be read from or written to the unit or channel.
•
R – The information can only be read from the unit or channel.
•
FCN – The command invokes a function in the unit.
3-6.
Command Format
The communication protocol incorporates the concept of 'Directed' and 'Global' commands at both the Unit and Channel
level with the following characteristics;
•
Unit or Channel numbers =0 are global commands that affect either all units or all channels of a particular unit
or both.
•
Directed commands that set a unit parameter are always acknowledged (ACK) with an ASCII message that
indicates '<Unit#>:<CMD>:ok’ if implemented with no errors or NAK with; <Unit#>:<CMD>:=<error#>’ if
an error was encountered.
•
Directed commands that request a particular parameters setting (query) result in a query response being
returned
•
No response is ever given to a Global Unit command.
Command Format:
'Unit#:Ch#:Cmd[=|?]{<value1 >{,< value2 >}}{;Ch#:Cmd[=|?]{<value1>{,< value2>}}}\n\r
•
Each message must be preceded by a Unit# & Channel# (both of which could be 0)
•
Messages may contain multiple commands separated by a semicolon ‘;’.
•
The second and subsequent commands in a message shall not contain a unit number but shall contain a channel
number.
•
Each command in a message will evoke a response message if one is warranted (not global)
•
Query’s ('?') can only be directed to one unit but if the channel=0 then each channel's setting will be returned in
the order 0-MAXCHANNELS separated by a ':'
Command examples:
1:0:GAIN=100.2\r\n
unit 1,all channels gain set to 100.2
1:1:GAIN=100.2;2:GAIN=120.3\r\n
unit 1, channel 1 gain = 100.2; channel 2 gain = 120.3
1:3:GAIN=100.2;0:FLTR=1\r\n
unit 1, channel 3 gain = 100.2; all channel’s filter = ON
General Query Response Format
Unit#:Cmd:Ch#=<value>{; Ch#=<value>}…>{; Ch#=<value>}…\r\n
Responses to a query with a channel number=0 will return the setting of each channel in a list separated by
semicolons ‘;’.
If the target of the query is a unit setting (ex. current excitation) then the channel number returned is the 1
st
channel of the board that processed the command.
3-7.
Multiple Board Models
All of these models have multiple main boards installed which will appear as a contiguous set of channels,
when in fact, physically, they are completely separate and operate somewhat independently. This presents some
interesting communication challenges. For instance, a global channel command to set 8 channels on a unit will
be handled by each internal board simultaneously. However only the board with the channels designated as 1-4
will ACK the command, the other board will remain silent.