Comtech EF Data RCS20 - Manual (Page 147)

RCS20 M:N Redundancy Switch Revision 15
Remote Operations MN-RCS20 and CD-RCS20
A–5
overflows and begins again at zero. The FSN tag is a powerful tool that assures sequential information
framing, and is especially useful where commands require more than one message packet. The full
handshake/acknowledgment involves a reversal of source and destination ID codes in the next message
frame, followed by a response code in the field of the message packet from the equipment
under control.
If a command packet is sent and not received at its intended destination, a timeout condition can occur
because the packet originator does not receive a response message. On receiving devices slaved to an
M&C computer, the timeout delay parameters may be programmed into the equipment in accordance with
site requirements by Radyne Corp. prior to shipment, or altered by qualified personnel. The FSN
handshake routines must account for timeout delays and be able to introduce them as well.
A.1.4 Global Response Operational Codes
In acknowledgment (response) packets, the operational code field of the message packet is
set to 0 by the receiving devices when the message intended for the device is evaluated as valid. The
device that receives the valid message then exchanges the with the ,
sets the to zero in order to indicate that a good message was received, and returns the
packet to the originator. This "GOOD MESSAGE" Opcode is one of nine global responses. Global
response Opcodes are common responses issued to the M&C computer or to another device that can
originate from and are interpreted by all Radyne equipment in the same manner. These are summarized
as follows (all Opcode values are expressed in decimal form) in Table A-2:
Table A-2. Response OPCODES
Response OPCODE Description OPCODE
Good Message 000d = 0000h
Bad Parameter 255d = 00FFh
Bad Opcode 254d = 00FEh
Bad Checksum 253d = 00FDh
Command Not Allowed in LOCAL Mode 252d = 00FCh
Command Not Allowed in AUTO Mode 251d = 00FBh
Bad Destination 250d = 00FAh
Unable to Process Command 249d = 00F9h
Packet Too Long 248d = 00F8h
Incomplete Parameter 247d = 00F7h