6100 ADCCP Programming Manual

(67) MODE SET
Requests and Responses
069225 Tandem Computers Incorporated 6–29
(67) MODE SET The MODE SET request and response are used to handle mode-setting frames.
Request The MODE SET request causes ADCCP to send a mode-setting frame on the line to
accept a mode-setting frame if it arrives, or to disconnect a station or put it in the
DEAD mode.
If the station is a primary or combined station, this request causes ADCCP to send a
mode-setting frame to the specified remote station. The request finishes successfully
when a UA or DM frame arrives from the station. In a SABM or SABME sequence, an
arriving SABM or SABME frame also completes the request.
If a recoverable error (such as a temporary line hit) occurs during the sequence,
ADCCP tries to send its frame again. If, after the maximum number of retries
(L2RETRIES), the request does not succeed, or if the requested sequence is inconsistent
with the line configuration (for example, your application requests a SARM sequence
on a line that supports only NRM), ADCCP puts the station in DEAD mode with the
ERRORSTOP condition. (To revive the station, use a (70) CHANGELIST request.)
If the local station is a secondary station, the MODE SET request makes the station
receptive to a mode-setting frame. Unless you specify DEAD or SIM as the desired
mode, ADCCP puts the station in DISC mode, so it can respond to mode-setting
commands. (If your application specifies a mode other than DEAD, DISC, or SIM in
this case, ADCCP still puts the station in DISC mode.) If you choose DEAD, the
station does not respond to any mode-setting command. If you choose SIM, the
station transmits RIM frames until it receives a SIM.
A primary or combined station can transmit data as soon as the MODE SET request
finishes. A secondary station must first issue a RECEIVETEXT request to find out
when a mode-setting frame arrives from the primary.
The request buffer format is:
Function := 67
Modifier := 0
Request ID := A unique value from 1 through 32767,
determined by the application
Text Out := Number of stations affected multiplied by 2
Text In := Number of stations affected multiplied by 2
Text := For each station affected:
Station ID :Byte
Use the number assigned to the station
in the DEFINELIST request. Use 0 to
indicate all stations.
New mode :Byte
0 = DEAD
1 = DISC