Siemens DataNET Hub (DNH) user manual Command Descriptions

Command Descriptions, Continued

dn window

dn window num

dn polldelay

dn polldelay time

dn portdelay

Displays the transmit “window” for the HDLC protocol used by DataNET. This is the number of I-frames that a station may send before it must receive an acknowl- edgment from the receiving station.

Sets the transmit window used by all ports on the hub. The parameter “num” must be a number 1 through 7. The de- fault window size is 7. The hub does not store the window size parameter in non- volatile memory, so non-default values will be lost after a reset.

The “poll delay” parameter applies only to ports 1-8 on a hub. It controls the time a hub will wait between polls of any port. As soon as a hub finishes an exchange of messages on one port, it will normally advance immediately to the next “con- nected” port and begin the next ex- change of messages. If “poll delay” is set to a non-zero value, the hub will enforce a delay before each new exchange be- gins. The “poll delay” is given in millisec- onds and defaults to zero (no delay).

Sets the poll delay to the value given, in milliseconds. Actual times are rounded down to the nearest ten milliseconds.

This parameter gives the delay, in milli- seconds, that a hub will enforce between message exchanges with a particular slave device. That is, before initiating a poll to a slave device, the hub will make sure that at least this much time has elapsed since the last poll to the same device. This keeps a hub from consum- ing all of the slave device’s processing time by continuously polling it at short intervals. This parameter defaults to 50 milliseconds.

76 • Command Summary 2000585-001