Epson TM-T20 User manual

ESC/POS Quick Reference
ESC/POS®Command System
EPSON ESC/POS is a proprietary POS printer command system based on the
escape sequence and includes patented or patent pending commands. ESC/POS is
compatible with most type of EPSON POS printers and displays.
ESC/POS is designed to reduce the processing load on the host computer in POS
environments. It comprises a set of highly functional and efficient commands and
also offers the flexibility to easily make future upgrades.
Aim of the Quick Reference
Quick Reference is a guide to using ESC/POS command to control the printer.
Command Notation
• RT : real-time command (executed as soon as received)
• fn= : function number of the command
• Numbers are written in decimal numeral.
• nspecifies 1 byte parameter in the range 0–255.
• nL, nHspecify 1 word (2 bytes) parameter as (nL+n×256) in the range
0–65,535.
• pL, pH specify the number of parameters after pH as (pL+pH×256) in the range
1–65,535
• p1, p2, p3, p4 specify the number of parameters after p4 as
(p1+p2×256+p3×65,536+p4×16,777,216) in the rage 1–4,294,967,295.
• kc1, kc2 specify key code (2 bytes) of NV graphics or download graphics. Each
range of kc1 and kc2 is 32–126.
• Control codes are as follows:
name code
NUL 0
EOT 4
ENQ 5
HT 9
LF 10
FF 12
CR 13
DLE 16
DC4 20
CAN 24
ESC 27
FS 28
GS 29
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written permission of Seiko Epson Corporation.
The contents of this document are subject to change without notice. Please contact us for the latest
information.
While every precaution has been taken in the preparation of this document, Seiko Epson Corporation
assumes no responsibility for errors or omissions.
Neither is any liability assumed for damages resulting from the use of the information contained
herein.
Neither Seiko Epson Corporation nor its affiliates shall be liable to the purchaser of this product or
third parties for damages, losses, costs, or expenses incurred by the purchaser or third parties as a
result of: accident, misuse, or abuse of this product or unauthorized modifications, repairs, or
alterations to this product, or (excluding the U.S.) failure to strictly comply with Seiko Epson
Corporation's operating and maintenance instructions.
Seiko Epson Corporation shall not be liable against any damages or problems arising from the use of
any options or any consumable products other than those designated as Original EPSON Products or
EPSON Approved Products by Seiko Epson Corporation.
EPSON and ESC/POS are registered trademarks of Seiko Epson Corporation in Japan and other
countries/regions.
M00051201
Print Commands
• In page mode, these commands only move the print position and do not execute
actual printing.
LF Prints data and feeds one line.
CR Functions the same as LF when auto line feed is enabled.
CR is ignored when auto line feed is disabled or when the
serial interface model is used.
ESC J nPrints data and feeds paper ndots.
ESC d nPrints data and feeds paper nlines.
Line Spacing Commands
ESC 2 Selects default line spacing.
ESC 3 nSets line spacing to ndots.
Character Commands
ESC SP nSets right-side character spacing to ndots.
ESC −nSelects underline.
n= 0: underline off, n= 1: 1-dot width, n= 2: 2-dot width
ESC E nTurns emphasized character On or Off.
n= odd: On, n= even: Off
ESC G nTurns double-strike character On or Off.
n= odd: On, n= even: Off
ESC M nSelects a character font.
n= 0, "0": Font A, n= 1, "1": Font B
GS ! nSelects character size (height/width magnification).
Upper 4 bits of n: width magnification
Lower 4 bits of n: height magnification
The both can be set 0(×1) to 7(×8)
GS b nTurns smoothing On or Off for magnified characters.
n= odd: On, n= even: Off
GS B nTurns white/black reverse print On or Off for characters.
n= odd: On, n= even: Off
ESC { nTurns upside-down print mode On or Off in standard
mode.
n= odd: On, n= even: Off
ESC V nTurns 90° clockwise rotation On or Off for characters in
standard mode.
n= 1, 2, "1", "2": On, n= 0, "0": Off
ESC & 3 c1 c2 [x1 d1...d(3 × x1)]...[xk d1...d(3 × xk)]
Defines user-defined characters for character code: c1 to
c2 of the current font.
x= width of the defined pattern
d1...d(3×x) = pattern data for a character
ESC % nSelects or cancels user-defined character set.
n= odd: Select, n= even: Cancel
Character Commands (continued)
ESC ? nCancel the user-defined character and return the font
pattern to the resident one for the current font.
n= character code to be cleared the user-defined font
ESC t nSelects page nfrom the character code table.
ncode table ncode table
0 PC437: USA, Standard Europe 34 PC855: Cyrillic
1 Katakana 35 PC861: Icelandic
2 PC850: Multilingual 36 PC862: Hebrew
3 PC860: Portuguese 37 PC864: Arabic
4 PC863: Canadian-French 38 PC869: Greek
5 PC865: Nordic 39 ISO8859-2: Latin2
11 PC851: Greek 40 ISO8859-15: Latin9
12 PC853: Turkish 41 PC1098: Farsi
13 PC857: Turkish 42 PC1118: Lithuanian
14 PC737: Greek 43 PC1119: Lithuanian
15 ISO8859-7: Greek 44 PC1125: Ukrainian
16 WPC1252 45 WPC1250: Latin2
17 PC866: Cyrillic #2 46 WPC1251: Cyrillic
18 PC852: Latin2 47 WPC1253: Greek
19 PC858: Euro 48 WPC1254: Turkish
20 KU42: Thai 49 WPC1255: Hebrew
21 TIS11: Thai 50 WPC1256: Arabic
26 TIS18: Thai 51 WPC1257: Baltic Rim
30 TCVN-3: Vietnamese 52 WPC1258: Vietnamese
31 TCVN-3: Vietnamese 53 KZ-1048: Kazakhstan
32 PC720: Arabic 255 User-defined page
33 WPC775: Baltic Rim
ESC R nSelects an international character set by n.
ncountry ncountry
0 USA 9 Norway
1 France 10 Denmark II
2 Germany 11 Spain II
3 U.K. 12 Latin America
4 Denmark I 13 Korea
5 Sweden 14 Slovenia/ Croatia
6 Italy 15 China
7 Spain I 16 Vietnam
8 Japan 17 Arabia
Print Position Commands
HT Moves print position to the next horizontal tab position.
ESC D n1...nk NUL
Sets tab stops at n1 to nk character columns.
GS L nL nH
Sets left margin in standard mode.
nL + nH×256: number of dots for left margin
GS W nL nH
Sets print area width in standard mode.
nL + nH×256: number of dots for print area width
ESC a nAligns all data in one line to the selected layout in
standard mode.
n= 0, "0": Left justification
n= 1, "1": Centering
n= 2, "2": Right justification
Copyright© 2012 Seiko Epson Corporation. All rights reserved.

Print Position Commands (continued)
ESC $ nL nH
Moves print position from the left edge of print area.
nL + nH×256: absolute print position
ESC \ nL nH
Moves the print position from current position.
nL + nH×256: relative print position (-32,768–32,767)
Panel Button Commands
ESC c 5 nEnables or disables the panel buttons.
n= odd: Disable, n= even: Enable
Mechanism Control Commands
GS V mExecutes paper cut.
m= 0, "0", 1, "1"
GS V m n Executes paper cut after feeding ndots.
m= "A" or "B"
Bit Image Commands
ESC ∗m nL nH d1...dk
Stores bit image data in the print buffer.
nL + nH×256: number of horizontal dots
d: image data (column format)
m
vertical
density
horizontal
density
vertical
dots
number of d
(= k)
0
203/3 dpi
203/2 dpi
8 dots nL + nH×256
1
203 dpi
32
203 dpi
203/2 dpi
24 dots 3×(nL + nH×256)
33
203 dpi
Graphics Commands
GS ( L pL pH 48 112 48 bx by 49 xL xH yL yH d1...dk fn=112
GS 8 L p1 p2 p3 p4 48 112 48 bx by 49 xL xH yL yH d1...dk
Stores graphics data in the print buffer to the magnified
size specified by bx, by.
bx = 1 or 2: horizontal magnification
by = 1 or 2: vertical magnification
xL + xH×256: number of horizontal dots
yL + yH×256: number of vertical dots
GS ( L 2 0 48 50 or GS ( L 2 0 48 2 fn=50
Prints graphics data in standard mode.
NV Graphics Commands
GS D 48 67 48 kc1 kc2 48 49 d1...dk fn=67
Converts Windows BMP data and defines NV graphics data
to key code (kc1, kc2).
NV Graphics Commands (continued)
GS ( L pL pH 48 67 48 kc1 kc2 1 xL xH yL yH 49 d1...dk or fn=67
GS 8 L p1 p2 p3 p4 48 67 48 kc1 kc2 1 xL xH yL yH 49 d1...dk
Defines NV graphics data to key code (kc1, kc2).
xL + xH×256: number of horizontal dots
yL + yH×256: number of vertical dots
GS ( L 6 0 48 69 kc1 kc2 x y fn=69
Prints NV graphics of key code (kc1, kc2) to the magnified
size specified by x, y.
x= 1 or 2: horizontal magnification
y= 1 or 2: vertical magnification
GS ( L 2 0 48 48 or GS ( L 2 0 48 0 fn=48
Transmits the entire capacity of NV graphics area.
Send data: "70" + Size + NUL
Size: "0"–"99999999" [bytes]
GS ( L 2 0 48 51 or GS ( L 2 0 48 3 fn=51
Transmits the unused capacity of NV graphics area.
Send data: "71" + Size + NUL
Size: "0"–"99999999" [bytes]
GS ( L 4 0 48 64 "KC" fn=64
Transmits the key code list for defined NV graphics.
Send data: "7r" + Is + [kc1,kc2]... + NUL
Is = 65: following send data group exists, Is = 64: not exist
[kc1,kc2]...: strings of key codes (0–80 bytes length)
GS ( L 5 0 48 65 "CLR" fn=65
Deletes all NV graphics data.
GS ( L 4 0 48 66 kc1 kc2 fn=66
Deletes NV graphics data of key code (kc1, kc2).
Download Graphics Commands
GS D 48 83 48 kc1 kc2 48 49 d1...dk fn=83
Converts Windows BMP data and defines download
graphics data to key code (kc1, kc2).
GS ( L pL pH 48 83 48 kc1 kc2 1 xL xH yL yH 49 d1...dk or fn=83
GS 8 L p1 p2 p3 p4 48 83 48 kc1 kc2 1 xL xH yL yH 49 d1...dk
Defines download graphics data to key code (kc1, kc2).
xL + xH×256: number of horizontal dots
yL + yH×256: number of vertical dots
GS ( L 6 0 48 85 kc1 kc2 x y fn=85
Prints download graphics of key code (kc1, kc2) to the
magnified size specified by x, y.
x= 1 or 2: horizontal magnification
y= 1 or 2: vertical magnification
GS ( L 2 0 48 52 or GS ( L 2 0 48 4 fn=52
Transmits the unused capacity of download graphics area.
Send data: "72" + Size + NUL
Size: "0"–"99999999" [bytes]
Download Graphics Commands (continued)
GS ( L 4 0 48 80 "KC" fn=80
Transmits the key code list for download graphics.
Send data: "7s" + Is + [kc1,kc2]... + NUL
Is = 65: following send data group exists, Is = 64: not exist
[kc1,kc2]...: strings of key codes (0–80 bytes length)
GS ( L 5 0 48 81 "CLR" fn=81
Deletes all download graphics data.
GS ( L 4 0 48 82 kc1 kc2 fn=82
Deletes download graphics data of key code (kc1, kc2).
Logo Print Commands
• User-defined NV graphics can be set to top or bottom logo.
• Top logo is printed in the events enabled by FS ( E (fn=64).
• Bottom logo is printed when paper cut command is executed.
FS ( E 6 0 62 2 kc1 kc2 a n fn=62
Sets for top logo printing in NV memory.
kc1, kc2: user-defined key code for the logo
a: logo position ("0"=left, "1"=center, "2"=right)
n: number of lines to be removed after the logo print
FS ( E 5 0 63 2 kc1 kc2 a fn=63
Sets for bottom logo printing in NV memory.
kc1, kc2: user-defined key code for the logo
a: logo position ("0"=left, "1"=center, "2"=right)
FS ( E pL pH 64 2 [a1 n1]...[ak nk] fn=64
Enables or disables auto top logo printing.
afunction
48 Prints while feeding paper to cut position
64 Prints at power-on
65 Prints when Roll paper cover is closed
66 Prints when buffers are cleared in recovery from error
67 Prints after fed paper with Feed button
n= "0": Disables, n= "1": Enables
FS ( E 4 0 65 2 a n fn=65
Enables or disables logo printing temporarily.
a= "0": Top logo n= "0": Enable
a= "1": Bottom logo n= "1": Disable
FS ( E 3 0 61 2 cfn=61
Transmits set values for top or bottom logo printing.
c= "0": Set values for top logo
c= "1": Set values for bottom logo
c= "2": Extended set values for top logo
csend data
"0" "7H202" + kc1 + kc2 + pos + line + NUL
"1" "7H212" + kc1 + kc2 + pos + NUL
"2" "7H222" + fa + fp + fc + fe + ff + NUL
kc1, kc2: user-defined key code for the logo
pos: logo position ("0"=left, "1"=center, "2"=right)
line: number of removed lines after logo print ("0"–"255")
fa, fp, fc, fe, ff: flag for top logo print ("0"=disabled, "1"=enabled)
fa: while feeding to cut position
fp: at power-on
fc: when cover closed
fe: when recovered from error with buffer clear
ff: when fed paper by switch

Logo Print Commands (continued)
FS ( E 6 0 60 2 c"CLR" fn=60
Clears set values in NV memory for top or bottom logo
printing.
c= "0": Top logo, c= "1": Bottom logo
Bar Code Commands
GS k m d1...dk NUL
Prints bar code. NUL terminates the data.
mbar code system number of d(=k)
0 UPC-A 11 or 12
1 UPC-E 6, 7, 8, 11 or 12
2 JAN13 / EAN13 12 or 13
3 JAN8 / EAN8 7 or 8
4 CODE39 1 or more
5 ITF even
6 CODABAR (NW-7) 2 or more
GS k m n d1...dn
Prints bar code. nspecifies the data length.
mbar code system number of d(=k)
"A" UPC-A 11 or 12
"B" UPC-E 6, 7, 8, 11 or 12
"C" JAN13 / EAN13 12 or 13
"D" JAN8 / EAN8 7 or 8
"E" CODE39 1 or more
"F" ITF even
"G" CODABAR (NW-7) 2 or more
"H" CODE93 1–255
"I" CODE128 2–255
"J" GS1-128 2–255
"K" GS1 DataBar Omnidirectional 13
"L" GS1 DataBar Truncated 13
"M" GS1 DataBar Limited 13
"N" GS1 DataBar Expanded 2–255
GS h nSets bar code height to ndots.
GS w nSets bar width of bar code.
n= 2–6 (thin–thick)
GS H nSelects print position of HRI characters.
n= 0, "0": Not printed
n= 1, "1": Above the bar code
n= 2, "2": Below the bar code
n= 3, "3": Both above and below the bar code
GS f nSelects font for the HRI characters.
n= 0, "0": Font A, n= 1, "1": Font B
Two-Dimensional Code Commands
GS ( k pL pH cn fn [parameters]
Stores, prints symbol data, or configure the settings.
cn = 48: PDF417
49: QR Code
50: MaxiCode
51: 2-dimensional GS1 DataBar
52: composite symbology
Two-Dimensional Code Commands (continued)
function fn
cn
48
49
50
51
52
S
tore symbol data in
memory 80
m d1...dk
m n d1...dk
m a b d1...dk
(m=48)
Print 2D symbol
81
m(m=48)
Send 2D symbol size 82 m(m=48)
Setting
columns
65
n
n1 n2
n
rows
66
n
module
67
n
n
n
n
row height
68
n
error
correction 69 m n n
options 70
m
maximum
width 71 nL nH nL nH
font
72
n
[parameters] (blank = invalid command)
Send data of GS ( k (fn=82):
"7" + Id + X+ 31 + Y+ 31 + "1" + 31 + Fl + Ec + NUL
number
of bytes
cn
48
49
50
51
52
Id
1
"/"
"6"
"7"
"O"
"P"
X: horizontal dots
1–5
"0"–"99999"
Y: vertical dots
1–5
"0"–"99999"
Fl: flag
1
"0" = printable, "1" = not printable
Ec: error code
0 or 4
N/A (0 byte)
"0000"–"9999"
Status Commands
DLE EOT nRT
Transmits real-time status as 1 byte.
n= 1: Printer status (binary: 0000xx00)
bit 2 = 1: Drawer kick-out connector pin 3: High
= 0: Drawer kick-out connector pin 3: Low
bit 3 = 1: in Offline, 0: in Online
n= 2: Offline cause status (0xx0xx00)
bit 2 = 1: Cover is open, 0: closed
bit 3 = 1: on feeding paper by switch, 0: not
bit 5 = 1: Printing stopped due to paper end, 0: not
bit 6 = 1: in Error state, 0: not
n= 3: Error cause status (0xx0x000)
bit 3 = 1: Autocutter error, 0: not
bit 5 = 1: Unrecoverable error, 0: not
bit 6 = 1: Automatically recoverable error, 0: not
n= 4: Paper end sensor status (0xx00000)
bit 5, 6 = 1: Paper end, 0: paper present
Status Commands (continued)
GS r nTransmits status specified by nas 1 byte after completion
of prior print or command.
n= 1, "1": Paper sensor status
Status = 0: Paper end sensor: paper present
Status = 12: Paper end sensor: not present
n= 2, "2": Drawer kick-out connector status
Status = 0: Drawer kick-out connector pin 3: Low
Status = 1: Drawer kick-out connector pin 3: High
GS a nEnables or disables basic ASB (Automatic Status Back).
bit of nStatus (1: enable, 0: disable)
0 Drawer kick-out connector status
1 Online/offline status
2 Error status
3 Paper end sensor status
ASB status binary (x=0 or 1)
first byte 0xx1 xx00
bit 2 = 1: Drawer kick-out connector pin 3: High
= 0: Drawer kick-out connector pin 3: Low
bit 3 = 1: in Offline, 0: in Online
bit 5 = 1: Cover is open, 0: closed
bit 6 = 1: on feeding paper by switch, 0: not
2nd byte 0xx0 x000
bit 3 = 1: Autocutter error, 0: not
bit 5 = 1: Unrecoverable error, 0: not
bit 6 = 1: Automatically recoverable error, 0: not
3rd byte 0110 xx00
bit 2, 3 = 1: Paper end, 0: paper present
4th byte 0110 1111
Macro Function Commands
GS : Starts or ends macro definition.
GS ^ r t m Executes defined macro.
r: repeat times
t: interval time (×100msec)
m= 0: repeat continuously
m= 1: repeat by pressing the Feed button
Miscellaneous Commands
ESC @ Initializes printer.
DLE ENQ n RT
Recovers from recoverable errors.
n= 1: Recovers and starts printing from the line where the error
occurred
n= 2: Recovers after clearing both receive and print buffers
GS ( D pL pH 20 [a1 b1]...[ak bk]
Enables or disables real-time command.
a= 1: DLE DC4 (fn=1) b= 0, "0": Disable
a= 2: DLE DC4 (fn=2) b= 1, "1": Enable
ESC = nEnables or disables the printer device.
n= 1, 3: Enable, n= 0: Disable

Miscellaneous Commands (continued)
ESC p m t1 t2
Outputs pulse to Drawer kick-out port.
m= 0, "0": connector pin 2, m= 1, "1": connector pin 5
t1: on time (×2ms), t2: off time (×2ms)
DLE DC4 1 m t fn=1 RT
Outputs pulse to Drawer kick-out port in real-time.
m= 0: connector pin 2, m= 1: connector pin 5
t= 1–8: On time / Off time (×100 ms)
GS ( H 6 0 48 48 d1 d2 d3 d4 fn=48
Transmits process ID specified by (d1, d2, d3, d4) after
execution of prior print or command.
d=32–126: visible character
Send data: 55 + 34 + d1 + d2 + d3 + d4 + NUL
GS I nTransmits printer ID or printer information.
n
information
send data
1, "1"
Printer model ID
99
2, "2"
Type ID
2: supported Multi-byte character
3: not supported
35
Column emulation
mode
"=#0"+NUL: normal mode
"=#1"+NUL: 42 column mode
65
Firmware version
95+strings+NUL
depends on firmware
66
Manufacturer
95+"EPSON"+NUL
67
Printer name
95+"TM-T20"+NUL
68
Serial number
95+Serial number (10 bytes)+NUL
69
Type of mounted
additional fonts
95+strings+NUL
depends on printers
ex.) "KANJI JAPANESE"
GS g 0 0 nL nH
Initialize resettable maintenance counter.
nL + nH×256
counter
unit
20
Number of lines fed
lines
21
Number of head energizations
times
22
Number of lines fed (after the print
head was replaced)
lines
50
Number of autocutter operations
times
70
Duration of printer operation
hours
GS g 2 0 nL nH
Transmits value of resettable or cumulative maintenance
counter.
counter unit
nL + nH×256
resettable
cumulative
Number of lines fed
lines
20
148
Number of head energizations
times
21
149
Number of lines fed (after the
print head was replaced)
lines 22 150
Number of autocutter operations
times
50
178
Duration of printer operation
hours
70
198
Send data: 95 + Value + NUL
Value: "0"–"9999999999" (1–10 bytes length)
GS ( K 2 0 50 mfn=50
Selects print speed.
m= 0, "0": speed customized by GS ( E (fn = 5, a= 6)
m= 1–13 (slow–fast)
Miscellaneous Commands (continued)
ESC ( A 3 0 97 n c fn=97
Sounds optional external buzzer.
nspecifies the sound pattern. (n= 1–7)
cspecifies the repeat times. (c= 0: infinitely)
DLE DC4 3 0 0 0 1 0 fn=3 RT
Stops sounding optional external buzzer and transmits 4
bytes: 55, 84, 64, 0.
DLE DC4 2 1 8 fn=2 RT
Executes printer power-off sequence and transmits 3
bytes: 59, 48, 0.
DLE DC4 8 1 3 20 1 6 2 8 fn=8 RT
Clears both receive and print buffers, and transmits 3
bytes: 55, 37, 0, as the Clear response.
Page Mode Commands
• Page mode is a free layout mode. Any print data can be put in any place on the
print area and be printed by FF or ESC FF command.
ESC L Switches from standard mode to page mode.
ESC S Switches from page mode to standard mode.
FF Prints all data and switches from page mode to standard
mode.
ESC FF Prints all data in page mode. After printing, the printer
does not clear the buffered data, the print position, and
values set by other commands.
ESC W xL xH yL yH dxL dxH dyL dyH
Sets the print area size and the logical origin in page
mode.
xL + xH×256, yL + yH×256: position of the logical origin
dxL + dxH×256: width of the print area
dyL + dyH×256: height of the print area
ESC T nSelects the print direction and the starting position in
page mode.
n print direction starting position
0, "0" left to right upper left
1, "1" bottom to top lower left
2, "2" right to left lower right
3, "3" top to bottom upper right
GS $ nL nH
In page mode, moves the vertical print position from the
starting position set by ESC T.
nL + nH×256: absolute print position
GS \ nL nH
In page mode, moves the vertical print position from the
current position.
nL + nH×256: relative print position (-32,768–32,767)
CAN Cancels print data in page mode.
Other Commands
• For details, refer to TM-T20 product specification or ESC/POS Application
Programming Guide for Paper Roll Printers.
• OC : obsolete command
Character Commands
ESC ! Selects character font and styles.
Miscellaneous Commands
GS P Sets horizontal and vertical motion units.
GS ( A Executes test print.
Bit Image Commands
GS v 0 Prints raster bit image OC
NV Bit Image Commands
FS q Defines NV bit image in NV graphics area. OC
FS p Prints NV bit image defined by FS q.OC
Downloaded Bit Image Commands
GS ∗Defines downloaded bit image. OC
GS / Prints downloaded bit image defined by GS ∗OC
Status Commands
ESC u Transmits peripheral device status as 1 byte. OC
ESC v Transmits status of paper sensor as 1 byte. OC
Mechanism Control Commands
ESC i Executes paper cut. OC
ESC m Executes paper cut. OC
Customize Commands
FS g 1 Writes data to NV user memory. OC
FS g 2 Transmits data in NV user memory. OC
User Setup Commands
GS ( E (fn=1) Enters User setting mode and transmits the mode
change notice.
GS ( E (fn=2) Ends User setting mode and performs software
reset.
GS ( E (fn=3) Sets memory switch setting values.
GS ( E (fn=4) Transmits memory switch setting values.
GS ( E (fn=5) Sets customized setting values.
GS ( E (fn=6) Transmits customized setting value.
GS ( E (fn=11) Sets configuration item for serial interface.
GS ( E (fn=12) Transmits configuration value.
GS ( E (fn=15) Selects configuration item: Class of USB interface.
GS ( E (fn=16) Transmits configuration value for Class of USB
interface.