The IEEE-1284 'C' cable pinout is shown below. | MDR Style Connector |
Pin # | Signal name | Pin Description and Function |
---|---|---|
1 | Busy | Busy |
2 | Select | Select |
3 | /nAck | Acknowledge |
4 | /nFault | Error |
5 | PError | Paper End |
6 | data0 | Address, Data Bit 0 |
7 | data1 | Address, Data Bit 1 |
8 | data2 | Address, Data Bit 2 |
9 | data3 | Address, Data Bit 3 |
10 | data4 | Address, Data Bit 4 |
11 | data5 | Address, Data Bit 5 |
12 | data6 | Address, Data Bit 6 |
13 | data7 | Address, Data Bit 7 |
14 | /nInit | Initialize |
15 | nStrobe | Strobe |
16 | /nSelectIn | Select In |
17 | /nAutoFd | Autofeed |
18 | HLH | Host Logic High |
19 | Ground | Signal Pin 1 GND |
20 | Signal Pin 2 GND | |
21 | Signal Pin 3 GND | |
22 | Signal Pin 4 GND | |
23 | Signal Pin 5 GND | |
24 | Signal Pin 6 GND | |
25 | Signal Pin 7 GND | |
26 | Signal Pin 8 GND | |
27 | Signal Pin 9 GND | |
28 | Signal Pin 10 GND | |
29 | Signal Pin 11 GND | |
30 | Signal Pin 12 GND | |
31 | Signal Pin 13 GND | |
32 | Signal Pin 14 GND | |
33 | Signal Pin 15 GND | |
34 | Signal Pin 16 GND | |
35 | Signal Pin 17 GND | |
36 | Peripheral Logic High | Signal from the Printer |
Personal Computer [PC] Parallel printer bus specification defines a
Point-To-Point asynchronous bi-directional interface. Devices may be
either 1284 compatible {older parallel port devices} or 1284
compliant. The maximum recommended length for a printer cable is 25 feet.
Centronics parallel cables run out to 12 feet maximum. The IEEE1284 cable
replaced the 'Centronics' cable, the Centronics interface is obsolete.
IEEE1284 operates in five different modes: [The connector or cable does
not change with each different mode, but the function of some of the pins
do]
Compatibility mode; Centronics type operation (PC to Peripheral),
providing the original (required) control signaling bits. These bits
include 8 data lines, a Strobe, a Busy, an Acknowledge, a Select, Paper
Empty, Fault, Initialize Printer, Select Printer, and a Auto Feed line.
Compatibility mode is the basic mode of operation, asynchronous, byte wide
operation with a transfer rate of between 50kBps to 150kBps.
Nibble mode; 4 bit data bus (Peripheral to PC), 8 bit data bus (PC
to Peripheral); supporting uni-directional printer interfaces. This
provides an interface which operates full speed forward and half speed in
reverse. The transfer rate is between 50kBps to 150kBps
Byte mode; 8 bit bi-directional bus. Normal port operation. The
transfer rate is between 50kBps to 150kBps
ECP; Extended Capabilities Port. Allowed the PC to send 32 bit
data to the port, than letting the port divide up the data into four 8
byte messages, improving system (PC) operation. Transfer speeds are ten
times faster then the previous modes.
EPP; Enhanced Parallel Port; Allows high-speed transfers of bytes
in either direction. EPP is used with real time controlled peripherals.
EPP transfer times are the same as ECP transfer rates.
Note; the mode of operation changes the function of the signals, not the ground lines which are the same regardless of the mode being used.
Pin | Compatibility mode | Nibble mode | Byte mode | EPP mode | ECP mode |
1 | Busy | PtrBusy | PtrBusy | nWait | PeriphAck |
2 | Select | Xflag | Xflag | User defined 3 | Xflag |
3 | nAck | PtrClk | PtrClk | Intr | PeriphClk |
4 | nFault | nDataAvail | nDataAvail | User Defined 2 | nPeriphRequest |
5 | PError | AckDataReq | AckDataReq | User defined 1 | nAckReverse |
6 | Data 1 | Data 1 | Data 1 | AD1 | Data 1 |
7 | Data 2 | Data 2 | Data 2 | AD2 | Data 2 |
8 | Data 3 | Data 3 | Data 3 | AD3 | Data 3 |
9 | Data 4 | Data 4 | Data 4 | AD4 | Data 4 |
10 | Data 5 | Data 5 | Data 5 | AD5 | Data 5 |
11 | Data 6 | Data 6 | Data 6 | AD6 | Data 6 |
12 | Data 7 | Data 7 | Data 7 | AD7 | Data 7 |
13 | Data 8 | Data 8 | Data 8 | AD8 | Data8 |
14 | nInit | nInit | nInit | nInit | nReverseRequest |
15 | nStrobe | HostClk | HostClk | nWrite | HostClk |
16 | nSelectIn | 1284 Active | 1284 Active | nAStrb | 1284 Active |
17 | nAutoFd | HostBusy | HostBusy | nDStrb | HostAck |
18 | Host Logic High | -- | -- | -- | -- |
19 | (Busy) ground return | ||||
20 | (Select) ground return | ||||
21 | (nAck) ground return | ||||
22 | (nFault) ground return | ||||
23 | (PError) ground return | ||||
24 | (Data 1) ground return | ||||
25 | (Data 2) ground return | ||||
26 | (Data 3) ground return | ||||
27 | (Data 4) ground return | ||||
28 | (Data 5) ground return | ||||
29 | (Data 6) ground return | ||||
30 | (Data 7) ground return | ||||
31 | (Data 8) ground return | ||||
32 | (nInit) ground return | ||||
33 | (nStrobe) ground return | ||||
34 | (nSelectIn) ground return | ||||
35 | (nAutoFd) ground return | ||||
36 | Peripheral Logic High |
The main IEEE-1284 bus page explains more about the interface.
Much of the IEEE-1284 electrical interface is not copied on each of the different styles pin outs, and not shown here.
The determining factor in using a particular connector defined by IEEE-1284 is determined by the gear that is already being used.
The links below point to the other pages related to the IEEE-1284 cable.
In each case these interfaces should not be used unless required, because they are out-dated.
The IEEE-1284 cable standard is stable and is no longer supported by a standards body, that is no updates are expected.
Many companies keep computer equipment until it can no longer be used or functions, so the IEEE-1284 still resides on a vast number of PC components.
The point, is to not upgrade to a system that has this style connector unless it's required to connect to some other pre-existing peripheral device.
In other words the IEEE-1284 connector is obsolete. A new PC will not have a IEEE-1284 connector, while a pre-installed working printer may.
It is not worth trying to get a PC vendor to install a IEEE-1284 connector to interface to a six year old printer.
Look instead to purchasing a new printer or using a USB to IEEE-1284 adaptor to make the PC to printer connection.
The USB to IEEE-1284 adaptor is the best upgrade option, and cheaper than buying a new printer.
Parallel Cable Port Pinout ....
Centronics Cable Pin-out ....
1284-A Cable Pinout .... 1284-B Cable Pinout
IEEE1284-A to 1284-B Adaptor
Pinout .. IEEE1284-A to 1284-C Adaptor
Pinout .. IEEE1284-B to 1284-C Adaptor
Pinout
In any case regardless of the IEEE-1284 interface being used, the standard is obsolete.
The data is listed here to assist in any attempted debug of an interface that is no longer functioning.
The electrical portion of the interface is simple TTL logic, and along with the connector has a low pin count.
However if the fault resides in the controller portion of the circuit than debugging may be a bit more difficult to repair.
This text only describes the portion of the circuit that drives the interface, not the processor that controls the entire device.
The reader should review both the main IEEE-1284 page and the related sub-pages, as possible suggestions are not re-listed on each topic.
Navigation: Engineering Home > Interface Buses > Cabled Interface Standards > IEEE-1284 Standard > C-Cable Variation.
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