Serial Communication
The IN1502 can be remotely controlled via a host computer or other device (such as a control system) attached to the rear panel Remote connector. The control device (host) uses Extron’s Simple Instruction Set (SIS) commands.
The scaler uses a protocol of 9600 baud, 1 stop bit, no parity, and no flow control.
The rear panel
Pin | Description |
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1 | – | No connection | 5 |
| 1 |
2 | Tx | Transmit data |
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3 | Rx | Receive data |
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4 | Input #1 | Contact closure |
| 9 | 6 |
5 | Gnd | Signal ground |
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6 | Input #2 | Contact closure | DB9 Pin Locations | ||
| Female | ||||
7 | – | No connection |
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8 | – | No connection |
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9 | Hardwired IR | IR input |
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RS-232 Programmer’s Guide
Host-to-scaler communications
SIS commands consist of one or more characters per field. No special characters are required to begin or end a command sequence. When the IN1502 determines that a command is valid, it executes the command and sends a response to the host device. All responses from the scaler to the host end with a carriage return and a line feed (CR/LF = 
), which signals the end of the response character string. A string is one or more characters.
It is also possible to send several SIS commands
Scaler-initiated messages
When a local event such as a front panel selection or adjustment takes place, the IN1502 scaler responds by sending a message to the host. No response is required from the host. The
(C) Copyright 2005, Extron Electronics, IN1502, Vx.xx 
The IN1502 sends the copyright message when it first powers on. Vx.xx is the firmware version number.
C hn X1
(where X1 is the input number)
The IN1502 sends this response when an input is switched.
Error responses
When the scaler receives a valid SIS command, it executes the command and sends a response to the host device. If the IN1502 is unable to execute the command because the command is invalid or it contains invalid parameters, it returns an error response to the host.
The error response codes and their descriptions are as follows:
E01 – Invalid input channel number
E10 – Invalid command
E13 – Invalid value (the number is out of range/too large)