UM-0085-B09
DT80 Range User Manual
Page 33
RG
Part B – Channels
Channel Definitions
A
channel definition
defines a measurement to be taken. It is therefore the fundamental building block that you use
when programming the DT80.
Channel definitions are normally enclosed in a
schedule definition
. The schedule definition specifies when to take the
measurements. The channel definitions specify what to measure, on which terminals and how to sample and process the
data value.
A sample schedule definition is shown below
RA2S 2DS 3R(4W) 2*V(0.1,GL3V,"Speed~km/h",FF0) 9CV(W)=9CV+1
This shows four channel definitions which are part of the "A" schedule. Each time this schedule runs (which will be every
2 seconds), four measurements will be taken:
1.
The logic state of digital channel 2 will be sampled
2.
A resistance connected to analog channel 3 (4-wire connection) will be measured
3.
A voltage connected to analog channel 2 (* and # terminals) will be measured and displayed as a speed value
4.
An internal general purpose variable will be updated (incremented)
Let us now examine the syntax of a channel definition more closely.
A channel definition consists of up to four components
•
the
channel type
is a mnemonic code which tells the DT80 what sort of quantity is being measured, or what
sort of sensor is attached. In the above example the channel types are
DS
(digital state),
R
(resistance),
V
(voltage) and
CV
(channel variable). A channel definition must always include a channel type.
•
a
channel number
prefix is required for most channel types. This specifies which channel to measure. In the
above example we are measuring digital channel
2
, analog channel
3
, analog channel
2*
and internal variable
#
9
•
channel options
are enclosed in round brackets after the channel type and further specify how the channel is
to be measured and processed. In the above example, the
3R
,
2*V
and
9CV
channels have user-specified
options, the
2DS
channel does not.
•
some channel types are "writable" (e.g. internal variables and digital output channels) and therefore allow a
value to be assigned using an
expression
. In the above example the
9CV
channel definition contains an
expression.
Channel Numbers
A DT80 channel number identifies a particular channel within a certain class of channels. The following table lists the
various classes of DT80 channels. As can be seen, each class has its own range of channel numbers.
Channel class
Terminal labels
Channel numbers
Applicable channel types
analog
1
–
16
(DT8x)
1
–
20
(CEM20)
1
–
16
n
01
–
n
20
(
n
= CEM20 number)
V HV I L R BGI BGV AS F FW T
x
AD5
xx
CU NI
LM
x
35 LM
xx
PT3
xx
TMP
xx
YS
xx
plus optional
* + – #
modifier
digital
1D – 8D
1
–
8
C DB DBO DN DNO DS DSO
counter
1C – 7C
1
–
7
HSC
phase encoder
1PE – 3PE
shared with counter
1
–
3
PE
relay
RELAY
1
RELAY
LED
Attn
1
WARN
serial
1 = serial sensor
2 = host RS232
3 = USB
1
–
3
SERIAL MODBUS
