Instructions
UM-0085-B09 DT80 Range User Manual Page 334
RG
• channel factor: for the single-bit types (DSO, RELAY, WARN) the channel factor is a delay value (ms). The
DT80 waits for the specified number of milliseconds after setting the output state. Default is 0, i.e. no delay. If
the R option is specified then the default and minimum delay setting is 10ms.
• R (reset) After setting the output bit(s) to the specified state(s) and waiting for the delay time, the output(s) will
then be set to the opposite state. In other words a pulse will be generated.
• PT (precise timing) – see Delay Accuracy (P40)
For example:
2DNO=1CV
will output the lower 4 bits of 1CV on outputs 5D, 4D, 3D and 2D (all other outputs wil be unchanged), while
2DNO(7)=1CV
(bitmask = 0111 binary) will output just the the lower 3 bits of 1CV on outputs 4D, 3D and 2D. For digital output 4D the
mask bit is 0 so its state will not be affected.
Digital Output Operation
All digital output channels are initialised to their default states on initial power-up or soft reset (INIT). Entering a new job
does not initialise the digital outputs.
A hard reset (power loss or
HRESET) will also normally re-initialise the digital output states. This behaviour can,
however, be overridden by setting:
PROFILE STARTUP MAINTAIN_OUTPUTS=YES
in which case digital outputs 1..8DSO and 1RELAY will be restored to their previous states following a hard reset.
The default states are summarised below:
Channel
Default state
Comments
1..4DSO (DT80/82I/85)
1..3DSO
(DT81/82E)
1 output pulled up (high), controlled load OFF
5..8DSO
(DT80/85)
4DSO
(
DT81/82E)
0 output driver disabled, pulled down (low)
1RELAY
0
contacts open
1WARN
0
LED off
Note: if one of the digital outputs or the latching relay is being used to control power to a modem (see Powering the DT80’s Modem
(P203)) then that output will not be reset during a soft reset (
INIT command).
A digital output command, e.g. 1DSO(20,R)=1 is processed as follows:
1. First, the output (or outputs for DNO/ DBO) is set to the specified state; if no state is specified (i.e. no =1 or =0 on
the end) then nothing is done.
2. Then the DT80 waits for the specified delay, if any. If a state was specified and the R option was also specified
then the default delay is 10ms, otherwise 0ms.
3. Then, if R is specified, the output(s) is/are inverted.
4. Finally, the output value as at Step 2 is returned.
The current state of any digital output is thus returned when a digital output command is evaluated. For example, typing
2DSO will return the state to which the output was last set. This will not necessarily reflect the actual state of the 2D
terminal (use
2DS to read the actual state). And if 2DSO(R) is entered then the state of 2D will be inverted and the
original state will be returned.
Connecting to Digital Outputs
As noted above, the two groups of digital channels have different electrical characteristics. In particular:
• Outputs 1D-4D (1D-3D for DT81/82E) use an open-drain FET output driver. This can sink up to 100mA @
30Vdc so it can drive a low voltage actuator or relay or LED directly. A 47k pull-up resistor (to approx. +4V) is
also included, allowing logic devices to be driven.
• Outputs 5D-8D (4D for DT81/82E, none for DT82I) are not suitable for directly driving loads such as relays or
LEDs. Logic devices can however be driven. Note that each of these output drivers is tri-stateable.
When the open-drain outputs are used to directly drive loads, the load will be on when the output is in the low state. Thus
if a load was wired up to output 1D you would use
1DSO=0 to turn the load on and 1DSO=1 to turn it off.
The default state of the output drivers on second group of channels is disabled (tri-stated). This allows these channels to
be used as inputs.