Tascam RC-898 User Manual

Section 9.1 - Controlling the parallel port device

9-1

9 – External control and
settings

This section covers the control of DTRS and other
units.

9.1 Controlling the parallel

port device

When a unit is connected to the

EXT 1

port [42]

of the RC-898, the transport may be controlled
usig the RC-898 transport controls. The pinouts
for these transport controls are given in 3.2.2,
“Parallel control/GPI pinout”.

To select the “parallel” unit for control:

1) Press the

MACHINE

key [31].

The

LOCATE TIME/VALUE

display will show

SELECT

2) Press

on the numeric keypad.

The

indicator on the machine number indica-

tors [8] will light, showing that the parallel port
unit is now selected for control.

9.2 Controlling GPI devices

Up to five GPI devices may be connected to the

EXT 1

port. These devices may be triggered at set

times, based on the times received for display on
the

TAPE TIME

display of the RC-898.

Refer to the documentation supplied with any
units to be controlled by GPI to find out whether
the unit requires the controlling circuit to be
closed or open in order to trigger the event, and
the time of the pulse needed to act as a trigger.

The wiring for the parallel port when used with
GPI devices is given in 3.2.2, “Parallel control/
GPI pinout”.

9.2.1 Setting up GPI devices

The polarity of the GPI devices, and the pulse
width necessary to trigger an event, may be set up
individually for each GPI device.

1) From menu group 1, move the cursor to

GPI

Setup

and press

SELECT

2) Holding down the

SHIFT

key, use the

NEXT

(

) and

PREVIOUS

(

DOWN

) keys to select

the required GPI unit.

3) Move the cursor to the

Pol

(polarity) field,

and use the

and

DOWN

keys to select either

open

for the polarity of the unit’s

event trigger.

When

open

is selected, the event is triggered

when the circuit is open (i.e. it is a “push-to-
break”-type circuit. When

is selected,

the event is triggered when the circuit is closed
(i.e.it is a “push-to-make”-type circuit).

4) Move the cursor to the

Width

field and use

the

and

DOWN

keys to select the pulse

width of the event trigger.

The minimum value for the pulse width is 0 ms,
and the maximum is 990 ms, settable in 10ms
increments.

Most GPI units require a trigger width of 200 ms.
If you are unsure of the trigger width for a particu-
lar device, we suggest that you try this value first
of all.

9.2.2 Setting the trigger points

The location memories also serve as GPI trigger
points, when GPI devices are connected to the

EXT 1

port.

Since up to 10 GPI events can be associated with
location memories, we suggest the following
method of working:

•

Use a “block” of location memories for this
purpose, starting at a number such as 80 or 90.

NOTE

The RC-898 provides only transport control for a unit con-
nected to the parallel port. Functions such as track arming,
etc. are not possible when using the

EXT 1

parallel port.

NOTE

Since the GPI event timings are based on the information
transmitted from the DTRS recorders connected to the RC-
898, the timing may “slip” by up to one frame.

G P I

S e t u p

G P I

P o l

W i d t h

o p e n

0 1 0

m S

NOTE

Note that the polarity setting here is also used as the polarity
setting for transport control signals sent to the E1 parallel
port device (

see 9.1, “Controlling the parallel port

device”

. In this case, the pulse width is fixed at 500 ms.)