Mantracourt DSC User Manual page 50

NOTES:
• From receipt of the host's terminating <CR> to a response from the device (if any) will be at most 50mS. After
this, it can be assumed there is no response.
• There is no value-checking: A slave can not NAK a command because a write data value is 'unsuitable' in some
way, only if write access itself is disallowed.
For the Ack-with-data (i.e. a successful read command), the returned value consists of printable ASCII characters
finishing with a <CR>, formatted according to the DP and DPB settings as follows
Write Command
If the device accepts the command then a <CR> is transmitted. There is no error checking on the data received by
the device.
Example:
A command to set the BAUD parameter to three on station 1 could look like this –
!001:BAUD=3<CR>
assuming a device with STN=1 is present, it will respond with –
<CR>
Read Command
Returns the requested value specified by the command.
The returned value is formatted according to the DP and DPB values: The response consists of a sign character (±),
DPB decimal digits before a decimal point, DP digits after the point and a terminating <CR>:
The length of the response is thus fixed at DP+DPB+3 characters.
Example:
A command to read the SOUT output could look like this –
!001:SOUT?<CR>
if the value=32.1, and format settings are DP=3 and DPB=5, the response string will be –
+00032.100<CR>
Action Command
If the device accepts the command then a <CR> is transmitted.
Example:
A command to reset device 14 would look like –
!014:RST<CR>
the response string will be just –
<CR>
Broadcast Commands
If the station address in a command message is "000", this means a broadcast command:.
All slaves act as normal on a broadcast command, but do not respond.
Example:
A command to all devices on the bus to sample their inputs would look like this –
!000:SNAP<CR>
- there is no response
Bad Commands
If any command is not understood by the device then a "?" is transmitted followed by a <CR>.
Example:
A unrecognised command, correctly addressed to station 173 –
!173:XYWR?<CR>
49 Micron Meters
DCell & DSC User Manual