Cloud Electronics DCM1 - Manual (Page 68)

DCM1 & DCM1e Installation and User Guide v1.0 68
The Configure Access Connector menu function permits
a slightly restricted set of I/O configurations of the eight pins:
inputs and outputs must be in consecutive “blocks”, e.g., pins
1 to 4 may be inputs with pins 5 to 8 as outputs. However,
using serial commands allows any combination of inputs and
outputs (up to a total of eight) to be set up. Examples are
given below.
Inputs:
In Input mode, the logic level present at a pin will be evaluated
as “high” (>2.55 V) or “low” (<0.75 V), and logic “active” =
“low”. The most common use of the GPIO port in Input
mode is to connect a pin to an external SPST push-button or
other type of N/O switch, with 0 V being applied to the other
contact. In Input mode, the pins are pulled-up internally to
+12 V, so an external switch closure will register as a low level
on interrogation, and this is interpreted as “active”.
Outputs:
In Output mode, the pins may be assigned to be “high”
(nominally +12 V) or low (nominally 0 V). External equipment
requiring a logic input may be connected to output pins,
provided the inputs are rated at not more than 24 V and do
not draw more than 60 mA.
Using Serial commands with the GPIO port:
RS-232 serial commands via either the RS232 INTERFACE
(DCM1 or DCM1e) or ETHERNET INTERFACE
(DCM1e only) may be used to set the configuration of the
PAGING ACCESS connector.
GENERAL FORMAT
FUNCTION COMMAND (ASCII)
Configure Connector for paging <PM,x/>
Configure Connector as GPIO port <SY.AC,Dxm/>
Set GPO(s) active <SY.AC,BSy/>
Clear all GPOs
<SY.AC,BPy/>
The results of these commands broadly correspond to the
options provided by the Configure Access Connector
menu function: the connector can be set for use with a paging
system, either as an input (Paging Zone Select) or output
(zone tallies), or as a GPIO port.
1. Configure for use with Paging mics
The value of x in the general format command <PM,x/> is
either ASCII “I” or “O”, configuring the connector for paging
zone selection or as a set of eight zone tallies respectively.
2. Configure as GPIO port
The value of x in the general format command
<SY.AC,Dxm/>
is again either ASCII “I” or “O”, with m
defining a number of pins on the connector to be GPI(s) or
GPO(s) respectively (where 1 ≤ m ≤ 8). In this mode, note
that pins set as inputs will always form a consecutive block
numbered ‘up’ from pin 1; likewise pins set as outputs will
always form a consecutive block numbered ‘down’ from pin
8. Thus in the third example below, pins 1 to 3 will be set
as GPIs, while pins 4 to 8 will remain as GPOs. A command
setting a pin to the same I/O state as its current state will
have no effect.
3. Set GPOs active
Once pins have been defined as outputs in GPIO mode, each
may be set “active” or reset “inactive” at will, using the general
format command <SY.AC,BSy/>. Here, y is an 8-bit string
consisting of either ASCII “X”s or “O”s. An “X” will set an
output “active”, and its in-string position refers to the the pin
number, as shown in fourth example below.
EXAMPLE COMMAND
Configure
Access
Connector for
paging zone
selection
ASCII
<PM,O/>
HEX 3C 50 4D 2C 4F 2F 3E
Configure
Access
Connector as
zone tallies
ASCII
<PM,I/>
HEX 3C 50 4D 2C 49 2F 3E
Configure
Access
Connector
as GPIO port
with 3 inputs
ASCII
<SY.AC,DI3/>
HEX 3C 53 59 2E 41 43 2C 44 49 33 2F 3E
Configure
Access
Connector
as GPIO port
with 3 outputs
ASCII <SY.AC,DO3/>
HEX 3C 53 59 2E 41 43 2C 44 4F 33 2F 3E
Set GPO 3
(pin 3) as
active ASCII <SY.AC,BSOOXOOOOO/>
HEX
3C 53 59 2E 41 43 2C 41 53 51 51 58
51 51 51 51 51 2F 3E
Clear all
outputs
ASCII
<SY.AC,BPXXXXXXXX/>
HEX
3C 53 59 2E 41 43 2C 41 50 58 58 58
58 58 58 58 58 2F 3E