Lectrosonics UDR200c - Manual (Page 22)

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LECNET COMMANDS
Poll Receiver - Retrieves a block of dynamic receiver status information, useful for polling from a control system.
Host sends command - 0 (0 hex)
Host receives 6 bytes - This is a packet of data reflecting the current status of the receiver. The contents
are as follows.
byte 1 - RF meter, antenna A (0=<1uV, 255=1mV)
byte 2 - RF meter, antenna B (0=<1uV, 255=1mV)
byte 3 - audio meter (0-255, 160 = clip level)
byte 4 - pilot tone detect status (0=absent, 1=present)
byte 5 - receiver internal temperature (30=46F,40=81F,50=116F)
byte 6 - tx battery voltage in tenths of volts, 0=not available
Get Device Name - Causes the receiver to send its “name” string back to the host.
Host sends command - 1 (1 hex)
Host receives length byte - 7 (decimal) This is the length of the string to follow.
Host receives name string - The 7-byte ASCII string, “UDR200C” or “UDR300C”.
Get Receiver Block - Retrieves the frequency block information for the receiver.
Host sends command - 4 (4 hex)
Host receives 1 or 2 data bytes - If the radio is on a standard block numbered 20-33, that number (deci-
mal) is returned as a one-byte response. If the radio is on a nonstandard three-digit block (e.g. 733), the
response is split into two bytes. To reconstruct the three-digit block, multiply the value of the first byte
received by 256 and then add the value of the second byte. Note that it is always possible to determine
from the first byte whether or not it will be necessary to receive a second byte. If the first byte is 20 or
greater, the radio is on a standard block and no further byte will be sent.
Set Channel - Tunes the receiver to the selected channel number.
Host sends command - 5 (5 hex)
Host sends channel as 2 bytes - Valid channel numbers are 0-255 (00-FF hex).
Because the
LecNet protocol only permits data values in the range 0-127 to be sent from the host, the channel number is
sent as two bytes, as follows.
byte 1 - For channel numbers from 0 to 127 decimal, this byte gets the channel number, unaltered.
For channel numbers 128 decimal or greater, this byte gets the channel number minus 128.
byte 2 - For channel numbers from 0 to 127 decimal, this byte is 0.
For channel numbers 128 decimal or greater, this byte is 1.
Host sends data byte - If this byte is nonzero, the new tuning will be remembered and restored if power is
lost. This is the normal behavior. If this byte is zero, the new tuning is temporary and will be lost if the radio
is powered off. This is useful for software that scans, since the tuning can proceed faster and the nonvolatile
channel memory is not unduly stressed.
Get Channel - Reads the currently tuned channel number.
Host sends command - 6 (6 hex)
Host receives data byte - This is the channel number (0-255 decimal, 00-FF hex).