INFICON VGC403 Three-Channel Measurement and Control Unit - Manual (Page 33)

tinb07e1-e 2011-07 Vacuum Gauge Controller
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S: Mnemonic [parameters]<CR>[<LF>]
R: <ACK><CR><LF> or <NAK><CR><LF>
6.2.3 Receiving (Unit --> Host)
The Host may request data from the unit. To this end the
Host first sends a message which describes what kind of
data is requested. The Vacuum Gauge Controller then
stores the requested data in the output buffer of the inter-
face.
Afterwards the Host sends the control character <ENQ>
to the unit. This prompts the unit to send to contents of
the output buffer to the Host.
In a symbolic representation this process can be illus-
trated as follows:
S: Mnemonic [parameters]<CR>[<LF>]
R: <ACK><CR><LF>
S: <ENQ>
R: Data<CR><LF>
If the Vacuum Gauge Controller receives a message
which cannot be interpreted (syntax error) it stores the
respective error status in the output buffer. See
Chapter 6.3.9 ERR,  36.
6.2.4 Examples
Inquiring the sensor identification
S: TID<CR>[<LF>]
R: <ACK><CR><LF>
S: <ENQ>
R: PSG,CDG,noSen<CR><LF>
Inquiring the sensor status
S: HVC<CR>[<LF>]
R: <ACK><CR><LF>
S: <ENQ>
R: 0,0,0<CR><LF>
Inquiring parameters of the switching function 1
S: SP1<CR>[<LF>]
R: <ACK><CR><LF>
S: <ENQ>
R: 0,2.0000E-01,5.0000E+00<CR><LF>
Inquiring parameters of the switching function 2
S: SP2,0,9E-1,2.2E0<CR>[<LF>]
R: <ACK><CR><LF>
S: <ENQ>
R: 0,9.0000E-01,2.2000E+00<CR><LF>
Setting the filter
S: FIL,1,2,1<CR>[<LF>]
R: <ACK><CR><LF>
S: <ENQ>
R: 1,2,1<CR><LF>
Behavior in case of a syntax error
S: FOL,1,2,1<CR>[<LF>]
R: <NAK><CR><LF>
S: <ENQ>
R: 0001<CR><LF>
6.2.5 Number formats
The following data is always stored in the exponential for-
mat in the Vacuum Gauge Controller:
• Pressure values
• Offset values
• Threshold values
Output
The above data is always output in the exponential for-
mat. A five-digit mantissa and a two-digit exponent are
used. Both parts of the number may contain a sign.
Symbolic representation: ±a.aaaaE±aa
Example: 1.2500E-01
In the case of logarithmic sensors (PSG, PCG, PEG,
MPG, BPG, BCG, HPG) the last two digits of the man-
tissa are always zero. Linear sensors (CDG) use all digits
of the mantissa.
Input
The above data may be input either in the exponential for-
mat or in the fixed point format. The input data is automat-
ically converted to the exponential format by the unit.
Example: 1.25E-1 and 0.125 are both valid input data.
6.2.6 Continuous transmission of
measurements
After the unit has been switched on, it starts to continu-
ously send measurements to the serial interface. By
default one set of measurements is sent every second.
The continuous measurement transmission stops when
the Host sends a character to the serial interface. The
transmission can be resumed with the COM command.
See Chapter 6.3.4 COM,  35.