Service manual

EXTERNAL SERIAL CONTROL PROTOCOL
B-7
April 2001
Part No. 001-9800-203
The diagram in Figure B-1 shows the message
flow for an external device to gain access to the
subscriber logic controller.
B.3.2 MESSAGE FORMATS
INFO BUS ACCESS PERMITTED
Function
: This opcode is used to signal to External
Devices that they may request access to the bus.
After power up it is sent periodically over the data
bus until an external device has registered. This is
always a broadcast message.
External Device Action
: If the External Device is
UNREGISTERED:
Upon reception of a BUS ACCESS
PERMITTED, the External Device must respond
with a POWER ON REQUEST message.
Otherwise, the message is ignored.
Origin
: Subscriber unit
Format
:
Data
: None
EVENT POWER ON REQUEST
Function
: This opcode is a request from the External
Device for service from the Subscriber Unit in
response to an INFO BUS ACCESS
PERMITTED message. This message is valid only
while the External Device is in the UNREGIS-
TERED mode. For this message the source address
is the broadcast address. The response to this
message is CMD POWER ON and contains an
assigned unit address. This message is one of the
directed events that does not get acknowledged.
Origin
: External Device
Serial Number
: A variable length serial number that is
returned in the CMD POWER ON.
Format
:
CMD POWER ON
Function
: This opcode is sent from the Subscriber
Unit in response to the EVENT POWER ON
REQUEST made by an External Device.
External Device Action
: Upon reception of a CMD
POWER ON message, the unit must act as
follows:
If Response Type = not allowed:
The External Device must remain in the “Unreg-
istered Mode” and must wait until the next INFO
BUS ACCESS PERMITTED message before
attempting another EVENT POWER ON
REQUEST message;
Otherwise, if Response Type = allowed:
the External Device must enter the “Standard
Command Mode” and begin normal operation.
The Response Type, if granted, indicates the
radio configuration and assigns the external
device’s bus address. The External Device
must transmit an acknowledge message upon
reception.
Origin
: Subscriber Unit
Format
:
Data
:
Response Type:
0x00 - Power On not allowed at this time
0x01 - Power On allowed
Opcode
1 byte
0x00
Opcode Serial Number
1 byte 0 to 16 bytes
0x02
Opcode
Response
Type
Radio
Model
Serial Number
1 byte 1 byte 8 bytes 0 to 16 bytes
0x03