Panasonic UF-E1 Service Manual page 165

c. ACCM
ACCM is a map for transmitting control codes transmissively (as data) on asynchronous links. As
shown in Figure 6.5.2.4, ACCM is a bit table with which each of 32-character control codes is identi-
fied and it is composed of 32 bits. For example, when the ACCM value is 001000h (bit 17 is ON),
the corresponding control code (DC1) is the subject of escape. Also, among those codes that are
set other than by ACCM, including escape code itself (7Dh) and flags (7Eh) must be escaped when
used as data.
In ACCM, there are receiving ACCM (32 bits) and transmitting ACCM (maximum of 256 bits in both
direction). In asynchronous mode, the default values for transmitting and receiving ACCM are
FFFFFFFFh (Escape all control codes). In other synchronous modes, these value swill be 0 (Noth-
ing is escaped.) The Appendix 2 of ISO3309-1991 (1/15/1992) stipulates HDLC under asynchro-
nous environment. In order to be compatible with this, DEL code (yFh) and the code with entry in the
highest bit of the control code designated in ACCM can be escaped.
In the ACCM setting, this can also be done as the LCP setting option. Figure 6.5.2.5 shows its struc-
ture.
Key Point
1
Indicates that control code with bit position from lower bit of 32 bit is sued
(Higher)
32 bit
ACCM Bit Map
(Value = 00010000h)
Control Code
32 byte
(Higher)
ACCM : Async Control Character Map.
Figure 6.5.2.4 Correspondence between ACCM and Control Code Table
Key Point
1
Composed of type, length, and ACCM bit map
Type (Value=2) Length (Value = 6)
1 byte
3
1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1Fh
ACCM bit map
1 byte 4 bytes (note)
Figure 6.5.2.5 Structure of LCP-ACCM setting option
(Bit Position)
2
17 (11th) ON
DC1 is used as the control code
DC1
11h
(Byte position: Hexadecimal)
2
Note: Transmitted from the upper byte.
161
1
Set as LCP setting optoin
UF-E1
(Lower)
0
NULL
00h
(Lower)