Enabling System Exclusive Messages; Ascii Character Data; Numeric Values; Nibble-Ized Data - Lexicon PCM 90 - MIDI IMPLEMENTATION DETAILS Midi Implementation Manual

PCM 90 MIDI Implementation Details Lexicon

Enabling System Exclusive Messages

The PCM 90 must be enabled via the front panel controls for receipt of System Exclusive messages. If
System Exclusive message receipt is not enabled, all System Exclusive messages are ignored. The
status of both the PCM 90 Memory Protect function and PCM 90 Pro and Go Edit modes are ignored when
System Exclusive messages are being received.

ASCII Character Data

Many of the System Exclusive messages include ASCII character data. This refers to the values between
0x20 (space) and 0x7F (delete). No other values should be used. Character fields should be padded with
spaces — the C NULL-terminator should not be used. When the PCM 90 receives an out-of-range value,
it will convert that value to a space. The small block character on the PCM 90 display (used to indicate
patch source/destination) is transmitted as a tilde. It is not possible to transmit this character to the PCM
90 via System Exclusive messages. The ASCII delete character (0x7F) maps to the large solid block on
the PCM 90 display. (This can be used in ADJUST and Custom Control strings, but not in effect names.)
The ASCII backslash character (0x5c) maps to the yen character (¥)on the PCM 90's display.

Numeric Values

Any numeric values greater than one byte are transmitted from least-significant to most-significant.

Nibble-ized Data

Some data (most importantly effect data) is transmitted in a nibble-ized format, i.e. each byte of data is
transmitted as a pair of bytes, with 4 bits of data in each byte. As in all other cases in the PCM 90, the less-
significant portion of the byte is transmitted first.

Data Errors

The PCM 90 will display System Exclusive errors when it encounters any of a number of problems,
including checksum errors and early termination of a System Exclusive message (too few characters).
It will also report back to the sender of a System Exclusive message if it cannot fulfill a legally formatted
request. This covers situation such as bank-not-present, etc.

Timing Considerations

As some messages require significant time to process, System Exclusive information should not be sent
to the PCM 90 in bursts of more than 3 messages every 20ms. The individual message descriptions
presented later in this document note any specific timeout requirements.

SysEx Automation

SysEx Automation is intended primarily for use by facilities using multiple PCM 90s in identical modes of
operation. This mode, which is enabled from the PCM 90 front panel, assumes that al units have the same
effects in the same locations and the same algorithm cards loaded, and that asingle master unit front panel
is controlling all slaved units. (Only front panel operations are transmitted as SysEx automation
commands.) Ideally, the master's Target ID (Control 3.4) should be set to All. The MIDI inputs of all slave
units must be connected directly to the master MIDI OUT. This requires a MIDI THRU box if there is more
than one slave. This is not an appropriate mode for effect editing.
The displays of the slaves do not necessarily track the display of the master, although the internal states
do. Although knob turns and button pushes are not transmitted, the actual parameter values are. This
guarantees that the slave units will be locked directly to the master values. The only exceptions to this are
the Tap, Compare and Bypass buttons, whose states are transmitted to the slaves because they change
the internal state of the device. The others are visual only.
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