Comtech EF Data SFC1800A - Manual (Page 48)

User Interfaces SFC1800A Synthesized Frequency Upconverter
4-24 TM111 - Rev. 1.0
The following response error codes are specific to the SFC1800A Upconverter:
SFC1800A Response Error Code Descriptions OPCODE
Remote Control Error 200h
Remote Time Error 201h
Remote Date Error 202h
Remote Frequency Error 203h
Remote Gain Error 204h
Remote Channel Error 205h
Remote Carrier Control Error 206h
Remote Input Attenuation Error 207h
Remote Converter Configuration Error 208h
Remote Backup Mode Error 209h
Remote Force Manual Backup Error 20Ah
Remote Learn Configuration Error 20Bh
Remote Backup Test Error 20Ch
Remote Compensation Control Error 20Dh
Remote Compensation Error 20Eh
Remote Priority Error 20Fh
4.4.2.5 Collision Avoidance
When properly implemented, the physical and logical devices and ID addressing scheme of the
COMMSPEC normally precludes message packet contention on the control bus. The importance
of designating unique IDs for each device during station configuration cannot be overemphasized.
One pitfall, which is often overlooked, concerns multi-drop override IDs. All too often, multiple
devices of the same type are assigned in a direct-linked "single-thread" configuration accessible
to the M&C computer directly. For example, if two Converters with different addresses
DESTINATION IDs are linked to the same control bus at the same hierarchical level, both will
attempt to respond to the M&C computer when the computer generates a multi-drop override ID
of 1. If their actual setup parameters, status, or internal timing differs, they will both attempt to
respond to the override simultaneously with different information, or asynchronously in their
respective message packets and response packets, causing a collision on the serial control bus.
To preclude control bus data contention, different IDs must always be assigned to the equipment.
If two or more devices are configured for direct-linked operation, then the M&C computer and all
other devices configured in the same manner must be programmed to inhibit broadcast of the
corresponding multi-drop override ID.
The multi-drop override ID is always accepted by devices of the same type on a common control
bus, independent of the actual DESTINATION ID. These override IDs with the exception of
“BROADCAST” are responded to by all directly linked devices of the same type causing
contention on the bus. The “BROADCAST” ID, on the other hand, is accepted by all equipment
but none of them returns a response packet to the remote M&C.